1987 3/4 ton 4x2 swap with 1/2 ton 4x4

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Luis of EP

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Okay so here is what i have
1987 3/4 ton r-20
5.7L V8
350 motor
TH400 transmission
ALL HD ( According to the RPO)
Rear axle; has a 14 bolt with 4.10 gears

I also have a donor truck
1987 1/2 ton v-10 (according to RPO)
5.0L V8
700R4 transmission
Transfer case; Unknown to me ( I Do have pic)
Front axle i believe is a Dana 44 ( it has 10 bolts)
Front suspension is HD according to RPO
Rear Axle is a 10bolt with gear ratio is 3.73
Came with 35in BF good wrench tires

So my question is if i wanted to make my 3/4 ton a 4x4 could i swap parts from the 1/2 ton over all i really want is the 700R4 transmission with the transfer case and the front axial (with the "HD" springs) i do know i will have to change the front axles gears to 4.10 to match my rear but is it/ or should it be a bolt off and on job for the front axle or not? what other things should i take into account? Or is the donor truck just useless to me?

will upload some photos i thought might help

I do plan on using this to haul and some occasional Texas desert trails so some advice would help tons.

I
:help:
 

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Last edited:

Luis of EP

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Here are some other pics off the 1/2 ton
 

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Luis of EP

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Here is the 3/4 ton 4x2 pics
 

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87sierra

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your transfer case looks like a New Process 261 but i am no expert

i would think your plan would work but if your going to use the truck to haul the amount a 3/4 ton truck can handle i would find a 3/4 ton front axle

i would also not use the 700r4 trans since they are known for problems

but i am no expert in this kinda of swap
 

Kapdin

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That front axle is a gm10 bolt not a dana. And yea as i hear if your going to work the truck at all stick with the th400. If its a daily driver for life the 700r4 and be nice to it. As far as swapping im sure itd doable but i hear its pretty involved but i have not rly looked into it so someone else will have to chime in.
 

Luis of EP

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So i have identified that my Tcase is a NP 208 according to the tag with a gear ratio of 2.61 what i got off the tag as well

I found a conversion kit for the TH400 that supposed to accept the NP208
http://racetransmissions.com/store/product_info.php/products_id/162. can i or should i put the np208 t case on my th400? or look for another t case?

Any ideas on what i should do?
 

Kapdin

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Id say if you got it and can match them up run it for sure. the only thing else id run would be an np205 but that 208 should be fine.
 

Luis of EP

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Would a Dana 60 from a 75 ford f250 fit or will it require modification?
 

Kapdin

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humm not much of a ford guy but i know the dana 44's from ford are high pinion's and the pumpkin's are driver side.
 

HotRodPC

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So i have identified that my Tcase is a NP 208 according to the tag with a gear ratio of 2.61 what i got off the tag as well

I found a conversion kit for the TH400 that supposed to accept the NP208
http://racetransmissions.com/store/product_info.php/products_id/162. can i or should i put the np208 t case on my th400? or look for another t case?

Any ideas on what i should do?

This IS NOT what you need. This is for converting from a 700r4 or Th350 2wd, to a Th400 2wd kit. You will not find "A Kit" To convert from 700r4/NP208 to Th400 2wd to Th400 and a NP208 off of a 700r4/NP208. You'll need to find the correct Th400 trans to accept the NP208, and you'll need to get the correct NP208 also. MIght be best to locate a Th400/NP208 or Th400/NP205 combo already married.
 

Luis of EP

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After i really looked at it your right on that conversion kit and im currently looking for either the bracket and a NP205 t case and as far as adding the t case with the bracket to my 3/4 ton could i still use the the regular drive shaft to connect my rear axle to it?? and then if i installed a D60 on my front end could i use the same front drive shaft off my donor truck?
 

HotRodPC

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NO, the 2wd REAR driveshaft will be way to long, it can be used, but will need shortened. Usually about $60-$80 at a driveline shop. If you go with a common combo, you can usually find a driveshaft at a Pull A Part type lot for about $25-$30 and if you luck out, might even have newer U joints in it. Standard U joints, and cheap, Special U Joints usually are not so cheap.
You can use the front Driveshaft, but will have to have a Special Ujoint to make the conversion from one size U joint to the other bigger U joint used on the Dana 60.
 

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