Pontiac powered GMC

[66-PMD-GMC]

I have been PM'ed several times about mounting a Pontiac V8 in a 63-66 Chevy/GMC so I thought I would pop a couple photos and some written words on the subject.
The easiest Pontiac V8 to install is a 70 and newer block. They have 5 motor mount holes on the side of the block (earlier blocks have only 2) so you can use what people refer to as the "clam shell" mount, a motor mount and a perch bracket from a 70-87 GM truck. (some people call the perch bracket a tower)
The earlier blocks will bolt in but I fabricate a "rail" to bolt to the side of the block so the "clam shell" bracket can be used.
The clamshell bracket I am referring to, in the photo I am posting, is sitting at the top of the 79 frame perch that I have the motor mount sitting on.
The photos I am posting show the parts needed and the trimming of the top of the frame rail that needs to be done. The frame rail needs to be trimmed 5/8's of an inch for the motor mount perches to bolt correctly to the top of the 63-66 frame.
The early firebird motor mounts look like they might work with the stock SBC motor mount perches but the spacing is different and they don't line up.
The Pontiac is much bigger than a SBC and it is just different.
However....
I also show a GMC V6 motor mount perch and I think when I was trying different things a few years back, that the earl 'bird mounts actually lined up with the V6 perch brackets but I don't know for sure.
If I have time soon, I will mock up a motor using those parts.
I hope this makes sense.
The Olds brackets used on the late 70's Olds diesel GM trucks will bolt an Olds motor right in too.. just an FYI

[jonzcustomshop]

I ended up using a 82 chev 3/4 ton 2wd motor mount, and a 77 poncho 455 in my wifes 63
all bolt in.
the 80's 3/4 ton mounts are taller than the 80's 1/2 ton, and fit right on the 63-66 frame.

[markeb01]

Thanks to both for sharing this information.

[66-PMD-GMC]

Originally Posted by jonzcustomshop

the 80's 3/4 ton mounts are taller than the 80's 1/2 ton, and fit right on the 63-66 frame.

I will be at the wrecking yards today.. I'll check that out.
Trimming the frame isn't hard but any step eliminated makes it easier..
And then you have all that Pontiac torque.... mo Power!

[vin63]

Originally Posted by jonzcustomshop

I ended up using a 82 chev 3/4 ton 2wd motor mount, and a 77 poncho 455 in my wifes 63
all bolt in.
the 80's 3/4 ton mounts are taller than the 80's 1/2 ton, and fit right on the 63-66 frame.

X2...this is basically what I've done in the past. Either that, or used the GM conversion block mounts (F body).

This last time, I used some leftover tubing and plate and fabricated my frame mounts...

[66-PMD-GMC]

Originally Posted by vin63

X2...this is basically what I've done in the past. Either that, or used the GM conversion block mounts (F body).

This last time, I used some leftover tubing and plate and fabricated my frame mounts...

I have seen those before.
Nice clean work and more room for exhaust.
I have explored bolt in conversions using existing parts as many of the guys on this site don't have the same fabrication skills as you or I may have...
Any ideas at all are good in my humble opinion...
Whatever it takes to get an Iron Indian motor into my truck