Driveshaft options for 1991 r3500 4wd conversion

Skyfall

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Ryan
Truck Year
1991
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r3500 Crew Cab 4WD
Engine Size
350ci
Hello All,

It has been a while since I've posted any information about the 1991 r3500 2wd to 4wd conversion that I am working on. I can report that everything is in place except for the important part that makes it a functioning 4x4 (transfer case!). I recently bought a 1983 K10 4x4 with a GM crate 350, Holley 4bbl, MSD ignition, factory A/C, tilt wheel, etc. AND...a recently rebuilt 700R4 mated to a rebuilt transfer case (NP208???). After taking the drive train out, I am going to sell the truck as a roller (long bed, 4" lift, 15x12 Alcoas, new 33" tires [bought by me], and NO rust). I bought it for $2k, which I thought was a STEAL. I am aware that swapping in the 700R4 is a step backwards from my current transmission, but it is what I have decided to do. From what I have read, the 700R4 needs 12 volts that cuts out when the brake pedal is applied and I need to mount the kick-down cable and make 10000% sure it is adjusted properly. If I am missing a huge step, please let me know!

My question is this:

What have other people done in regards to their rear driveshaft who have made this swap? Did you get the slip-yoke delete kit (ORD sells a kit) and shorten the factory driveshaft OR perhaps keep the slip-yoke and have a custom one piece driveshaft fabricated? Are there other options? I would but a new replacement driveshaft out of a 1991 v3500 if I could find one, but my searches have turned up nothing...

Thank you all in advance for your responses!

My truck in its current form:

1991 r3500, 84K original miles - 350 TBI, 4.11 gears, true duals and headers, ORD front and rear spring hangers, 6" suspension, 1" ORD body lift, factory 4x4 hump (yay), Carr steps, 31 gallon suburban / Blazer gas tank - fuel filler neck is in the fender-well, 15x12 Bart wheels, 16/35/15 Boggers (I had to grind about 1/8" off of the front calipers, but 15" rims will fit a 1 ton). The front axle is out of a 1984 K30, the bed is from a 1986 K20, the fenders are from a 1980's K20.

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Regards,
 

shiftpro

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Use a CV joint at the TC and point the pinion and driveshaft directly at the CV. Slip joint in the driveshaft. Long shocks and brake lines to allow for max suspension droop.
A shackle reverse setup poi ts the diff in almost the perfect place.
The shaft as I said from the pinion is pointed directly at the CV joint... no that's not right, it should point just slightly under, so that when you rat on it or are pulling through sand/muck in low range the axle wrap doesn't point that shaft above the CV.
But if you want a long travel rear suspension then you won't be running multi leafs for weight. That leaves you with a flexy suspension but then you need a traction bar/anti-wrap bar. Use airbags if you want to load it down, but they need to be 'hung' from above and sit in a cup mounted to the top of the axle. If your airbag is connected to the frame and rear housing you will have lost your droop.
 

shiftpro

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I hope you understood my post. Forgive me if it doesn't make any sense. Too hot today and I'm not feeling well right now.
 

shiftpro

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CalSgt

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My 2 cents...

Nothing against Tom Woods stuff @shiftpro recommends, its great stuff. I'm sure High Angle is great too they're a local shop to me and I've heard good stuff.

Here's the deal, any decent driveline service should be able to build you a custom shaft and get you lined out on set up.

Biggest advantage of a local driveline shop is shipping and customer service. If you have issues, shipping driveshafts back to tom woods in Utah or High Angle in Paradise, CA will be an expensive PIA.
 

Skyfall

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r3500 Crew Cab 4WD
Engine Size
350ci
Thank you all for your responses. What about converting my transfer case to a non-slip joint with the kit from ORD, then shortening my current driveshaft?
 

CalSgt

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Thank you all for your responses. What about converting my transfer case to a non-slip joint with the kit from ORD, then shortening my current driveshaft?
Odds are a driveline service can get you everything you need for the slip yoke elimination on the TC. Shortening an existing shaft is much cheaper than getting a new one made since they reuse the tube and tube yokes, you would just need a flange to mate to the TC added at one end.
 

Bextreme04

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K25
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350-4bbl
Hello All,

It has been a while since I've posted any information about the 1991 r3500 2wd to 4wd conversion that I am working on. I can report that everything is in place except for the important part that makes it a functioning 4x4 (transfer case!). I recently bought a 1983 K10 4x4 with a GM crate 350, Holley 4bbl, MSD ignition, factory A/C, tilt wheel, etc. AND...a recently rebuilt 700R4 mated to a rebuilt transfer case (NP208???). After taking the drive train out, I am going to sell the truck as a roller (long bed, 4" lift, 15x12 Alcoas, new 33" tires [bought by me], and NO rust). I bought it for $2k, which I thought was a STEAL. I am aware that swapping in the 700R4 is a step backwards from my current transmission, but it is what I have decided to do. From what I have read, the 700R4 needs 12 volts that cuts out when the brake pedal is applied and I need to mount the kick-down cable and make 10000% sure it is adjusted properly. If I am missing a huge step, please let me know!

My question is this:

What have other people done in regards to their rear driveshaft who have made this swap? Did you get the slip-yoke delete kit (ORD sells a kit) and shorten the factory driveshaft OR perhaps keep the slip-yoke and have a custom one piece driveshaft fabricated? Are there other options? I would but a new replacement driveshaft out of a 1991 v3500 if I could find one, but my searches have turned up nothing...

Thank you all in advance for your responses!

My truck in its current form:

1991 r3500, 84K original miles - 350 TBI, 4.11 gears, true duals and headers, ORD front and rear spring hangers, 6" suspension, 1" ORD body lift, factory 4x4 hump (yay), Carr steps, 31 gallon suburban / Blazer gas tank - fuel filler neck is in the fender-well, 15x12 Bart wheels, 16/35/15 Boggers (I had to grind about 1/8" off of the front calipers, but 15" rims will fit a 1 ton). The front axle is out of a 1984 K30, the bed is from a 1986 K20, the fenders are from a 1980's K20.

You must be registered for see images attach


Regards,
What are you converting FROM? A 91 would have been a 4L80E from the factory, right? Are you swapping a 4L80 for a 700R4? The 208 from that 700R4 would fit right on a 4wd 4L80
 

77 K20

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My 2 cents...

Nothing against Tom Woods stuff @shiftpro recommends, its great stuff. I'm sure High Angle is great too they're a local shop to me and I've heard good stuff.

Here's the deal, any decent driveline service should be able to build you a custom shaft and get you lined out on set up.

Biggest advantage of a local driveline shop is shipping and customer service. If you have issues, shipping driveshafts back to tom woods in Utah or High Angle in Paradise, CA will be an expensive PIA.

It all depends on where you live. For me there is basically just one shop in town for drivelines. Been here forever. I've heard the guy was a jerk. I drove to the shop and asked him about driveline modifications I needed and he just laughed. "For something like that just go to a junkyard. I'm not going to waste my time."

So I've had 3 drivelines made by Tom Woods. All 3 were done right the first time, and all were shipped out the day after I ordered them. And it was free shipping.
 

Bextreme04

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It all depends on where you live. For me there is basically just one shop in town for drivelines. Been here forever. I've heard the guy was a jerk. I drove to the shop and asked him about driveline modifications I needed and he just laughed. "For something like that just go to a junkyard. I'm not going to waste my time."

So I've had 3 drivelines made by Tom Woods. All 3 were done right the first time, and all were shipped out the day after I ordered them. And it was free shipping.
Amazing he's still in business with that attitude. I was looking at ordering one from Denny's driveline for my K20 if I ever decided to do the slip yoke eliminator kit on my NP205.
 

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