1978 c30 SM465 Crossmember Help

[Biggnate81]

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]

I only have one side (passenger of my 78 350 4sp 205) set up. Hope it helps...

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[SDJunkMan]

I only have one side (passenger of my 78 350 4sp 205) set up. Hope it helps...

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

 

[Biggnate81]

I only have one side (passenger of my 78 350 4sp 205) set up. Hope it helps...

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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]

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]

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]

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.

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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.

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[bucket]

That appears to be for a 1/2 or 3/4 ton truck.

 

[77GMC35]

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]

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.