Which generation easiest to swap?

[72gmcdiaz]

Which generation (47-54 55-59 60-66 67-72) of truck is easiest to swap in a 12v cummins without need to cut firewall?

in other words, which of these trucks have more engine bay space?
Ive seen many threads but some have cut firewalls some don't.

Im thinking of getting a 1 ton truck of any generation of these to swap in a 6bt nv4500 and use it as a tow rig

[Ziegelsteinfaust]

I have not done one, but I have dreamt of doing one.

The 60-72 years are the easiest, but still cutting the firewall is a typical option people follow. Or they move the radiator in front of the core support, and it gets crowded. Myself I would remove the cab, and set the engine where I want. Then lower the cab, and start the surgery.

The earlier trucks are narrower cabs. And yes people.have done it too. But real-estate aka foot room gets a bit tight. So alot of people do 4 cylinder swaps on those among the reasons.

The 6bt is a big girl, and luckily plenty of people have done it. So find the formula you like, and copy + paste. The reason some cut and some don't basically is. Either way you go you get a set of problems to deal with. Cutting the cab solves oil pan cross member issues. Moving the engine forward solves firewall issues. The reason I would cut the firewall is so some of the engine's mass is shifted to the rear for a better handling experience.

Damned if you do. Damned if you don't.

Finnegans garage did a swap on the ramp truck which is a pretty good brochure on them. Plus there has to be several in depth swaps on YouTube besides forums.

[Dewey72]

Did mine on a 72 short box 6bt nv4500 swap and didn’t have to cut the fire wall or move the radiator to the other side. I used a Autoworldmt crossmeber and it worked nice. Mine was a 4x4 so I put a 4” lift on it to help with the front axle clearance and put a 1” body lift just to help clearance issues but probably not needed. Not sure on the other years.
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[Dieselwrencher]

I've done a lot of 69 up swaps and never cut one firewall. I have rolled the floor to firewall seam to clear exhaust or make trans removal easier. I cringed when they cut the ramp truck's firewall. It didn't need done. But hey, it's not my truck.

The 50s and 40s trucks are definitely harder to swap and for sure will need firewall work to get them in there.

[rickcdewitt]

Man a 55-59 long fleet bed 1 ton with a cummins would be so sweet.4x4 would be even cooler. Not a small engine bay on those trucks?