drum to disc conversion

[sduckworth13]

I just recently bought a 1967 GMC 3/4 with manual steering, 8 lug drum/drum manual brakes and rear leaf springs w/o coils. I have been reading everything on the conversions and everyone says that the engine crossmember will bolt right up from 73-87 with just a few bolt hole mods. I went out and bought a complete suspension from a 1974 1/2 ton with disc/ drum. I bought the entire suspension which has 5 lug disc up front and drums in the back , steering ( steering wheel, gear box, idler arm, centerlink etc. and brake system ( lines and prop valve too). I didnt get the pump just figured I would buy a new one, along with hoses too. I was wondering if someone would guide me to what I can actually use for the swap. My questions are can i use my 3/4 ton crossmember and just swap the 1974 1/2 ton suspension or do I need to swap the entire suspension with the crossmember attached ? Can I swap the rearend out of the 1974 and use it ( leaf springs w/o coils) ? Can I use the power booster/ mstr cyl from the 74 Chevy 1/2 ton on my 1967 3/4 ton without any modifications to my firewall ? Thank you

[lolife99]

Originally Posted by sduckworth13

I just recently bought a 1967 GMC 3/4 with manual steering, 8 lug drum/drum manual brakes and rear leaf springs w/o coils. I have been reading everything on the conversions and everyone says that the engine crossmember will bolt right up from 73-87 with just a few bolt hole mods. I went out and bought a complete suspension from a 1974 1/2 ton with disc/ drum. I bought the entire suspension which has 5 lug disc up front and drums in the back , steering ( steering wheel, gear box, idler arm, centerlink etc. and brake system ( lines and prop valve too). I didnt get the pump just figured I would buy a new one, along with hoses too.
I was wondering if someone would guide me to what I can actually use for the swap.

My questions are can i use my 3/4 ton crossmember and just swap the 1974 1/2 ton suspension or do I need to swap the entire suspension with the crossmember attached?
Yes you can keep the 3/4 ton crossmember. I recommend it.
Plus this will allow you to disassemble all the 1/2 ton parts and inspect or replace them if needed.
(balljoints and tie rod ends. Look at the cross shaft bushings in the a-arms also)

Can I swap the rearend out of the 1974 and use it (leaf springs w/o coils)?
Is your 67 coil or leaf?
If your '67 is a coil spring truck,... you can purchase new rearend perches from ECE (www.earlyclassic.com) and also use their super track bar to replace your original panhard bar.


Can I use the power booster/ mstr cyl from the 74 Chevy 1/2 ton on my 1967 3/4 ton without any modifications to my firewall ?
Yes,... but you may have to drill a hole or two and modify the brake pedal rod. Otherwise you can use a 71-72 master cylinder and prop valve.

Thank you

Welcome.
Thanks for giving a very detailed question,... it helps alot.
I'll see if I can answer your questions.

[sduckworth13]

Thank you, I appreciate all your help Keith, and to answer your question about does the 1967 3/4 ton have coils, I do have leafs only on the 3/4 ton rear end w/o coils. I found a 1971 rear end that has the 5 lug drums. Would that be a better choice, I hear that its a direct swap.

[lolife99]

If you are switching to 5-lug,... the 71 rearend would be the perfect bolt-in replacement rearend.
Are you going with a stock height or a lowered ride height?

[sduckworth13]

Cool, good to know that its a direct swap from someone else not just the guy selling me the 71 rear end to me. I'm going to lower the ride height 4 1/2 in the front and 6 in the back. Going as low as I can without bags. I got a good deal on the 1974 chevy 1/2 ton paid $250.00 for the entire suspension, steering, brake setup. I could resist the price for all those parts. Eventually will up grade the control arms with tubular uppers and lowers.