1978 c30 SM465 Crossmember Help

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Biggnate81

Member
Joined
Apr 1, 2020
Posts
32
Reaction score
15
Location
Kentucky
First Name
Nathan
Truck Year
1976
Truck Model
C10
Engine Size
350
So the saga of mismatched parts on my c30 continues. I'm sure you all are getting tired of my posts by now since it seems like every couple of weeks I'm posting on here asking questions, but I definitely appreciate the wealth on knowledge on this site. I was curious if anyone has pictures of the SM 465 crossmember for the 1 ton trucks? I think i might have the wrong one in my truck, it was bolted to the bottom of the frame rail and i noticed that the top flange of the crossmember is about 2 inches below the top of the frame rail. Also the trans and motor are sitting at an angle leaning back. I took the crossmember loose from the bottom of the frame and jacked it up until the top flange could be bolted to the top frame rail, now the motor and trans are sitting level but now there's a 2 inch gap between the bottom of the crossmember and the bottom frame rail. Did these trucks have a bolt spacer for the bottom bolts of the crossmember? Or should the crossmember go from the top frame rail to the bottom frame rail?
 

dvdswan

Full Access Member
Joined
Mar 11, 2014
Posts
2,366
Reaction score
2,024
Location
Port Orchard, WA
First Name
Dave
Truck Year
1978
Truck Model
K10
Engine Size
350
I only have one side (passenger of my 78 350 4sp 205) set up. Hope it helps...

You must be registered for see images attach


You must be registered for see images attach
 

SDJunkMan

Full Access Member
Joined
Nov 17, 2017
Posts
1,792
Reaction score
2,627
Location
Black Hills of South Dakota
First Name
Jeff
Truck Year
1978
Truck Model
K10
Engine Size
350
I only have one side (passenger of my 78 350 4sp 205) set up. Hope it helps...

You must be registered for see images attach


You must be registered for see images attach

I think the 1 ton frame is taller than a 1/2 ton so that may not help.
 

Biggnate81

Member
Joined
Apr 1, 2020
Posts
32
Reaction score
15
Location
Kentucky
First Name
Nathan
Truck Year
1976
Truck Model
C10
Engine Size
350
I only have one side (passenger of my 78 350 4sp 205) set up. Hope it helps...

You must be registered for see images attach


You must be registered for see images attach

I know on my k10 it has the same crossmember as that. And my 1 ton frame is definitely taller and from what I've researched the crossmember sets inside the frame rails and bolts to the top and bottom but I havent been able to find a picture of one in the truck to know for sure. I think I can make mine work opposed to trying to source the proper crossmember. I'll try to get some pictures of mine posted up tomorrow.
 

dvdswan

Full Access Member
Joined
Mar 11, 2014
Posts
2,366
Reaction score
2,024
Location
Port Orchard, WA
First Name
Dave
Truck Year
1978
Truck Model
K10
Engine Size
350
I wasn't sure if there was a difference for the front crossmember between the 2 trucks. Just thought it would help as a reference.
 

Biggnate81

Member
Joined
Apr 1, 2020
Posts
32
Reaction score
15
Location
Kentucky
First Name
Nathan
Truck Year
1976
Truck Model
C10
Engine Size
350
I wasn't sure if there was a difference for the front crossmember between the 2 trucks. Just thought it would help as a reference.
One would think that chevy would have made one crossmember to fit all the squarebody frames but I guess not. From what I've been able to find it seems like they made several variants of crossmembers for the squares.
 

Biggnate81

Member
Joined
Apr 1, 2020
Posts
32
Reaction score
15
Location
Kentucky
First Name
Nathan
Truck Year
1976
Truck Model
C10
Engine Size
350
Here's some pictures of my crossmember. With it bolted to the bottom of the frame like it was when I got the truck, the motor is definitely leaning back and the z bar is at a steep angle.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach

When its jacked up so the the top of the crossmember can bolt to the top of the frame the motor is more level and the z bar is level. So I'm thinking that I have the wrong crossmember. But i could probably put some square tubing underneath the crossmember to act as a spacer between it and the frame and I don't think I'd have any issues with it.
You must be registered for see images attach
You must be registered for see images attach
 

77GMC35

Junior Member
Joined
May 19, 2019
Posts
1
Reaction score
0
Location
hudson, n.h.
First Name
richard
Truck Year
1977
Truck Model
c35
Engine Size
350 cu.in.
Nathan,
I have a 77GMC35......GVW10000......350ci....floor manual tran.
Refer to your last 2 photos:
My clutch bracket is level. motor is level. The cross member is bolted to the top and bottom of the frame. The only difference from your cross member is the part that extends to the lower part of the frame. Back-in-the-day, this was a 1 ton dump. Hope this helps you.
 

Biggnate81

Member
Joined
Apr 1, 2020
Posts
32
Reaction score
15
Location
Kentucky
First Name
Nathan
Truck Year
1976
Truck Model
C10
Engine Size
350
That appears to be for a 1/2 or 3/4 ton truck.

That was my thought on it.


Nathan,
I have a 77GMC35......GVW10000......350ci....floor manual tran.
Refer to your last 2 photos:
My clutch bracket is level. motor is level. The cross member is bolted to the top and bottom of the frame. The only difference from your cross member is the part that extends to the lower part of the frame. Back-in-the-day, this was a 1 ton dump. Hope this helps you.

Thanks, that's what I figured is it should bolt to the top and bottom of the frame. I'm thinking I'll take some square tubing and put on the bottom side so its good and solid.
 

Forum statistics

Threads
41,858
Posts
903,640
Members
33,372
Latest member
83elcowes
Top