305V6 differences
 

I’ve got a 66 Gmc 3/4 ton pickup that’s got a bad 305 v6 in it. I’d like to replace it with a 48,000 miles 305 I got out of a grain truck but I noticed the water pump/timing housings are different. My question is, can I make that big truck v6 work in that 3/4 ton? Or can I swap the intake and timing housings from the original to the bigger truck engine?

Re: 305V6 differences
 

I never done it before but pretty sure it can be done. On the block in front of the right side head will identify the cubic inches and whether it's a A,B,C D,E engine. Give that to the folks on the 6066 gmc forum. They should be able to help.

Re: 305V6 differences
 

Interesting if the grain truck was a tilt cab, those have different pulley set ups. The 305 block is the same and most all external parts are interchangeable. The real change comes when you get to the 401 and 478's.

Re: 305V6 differences
 

It wasn’t a cab over truck just a 4000 series. The motor that is in my 66 that I’m wanting to change is a 305E while the one from the grain truck is a 305 C. Not sure the difference but I also have a 351 on an engine stand that has the same timing cover and intake as the 305E. My guess would be it is a different cover for the big truck

Re: 305V6 differences
 

Few pictures of the pickup. Completely rust free but has definitely spent time on a farm

Re: 305V6 differences
 

Everything should swap over just fine, I've seen plenty of 351 and 478 truck swaps with 305 v6 parts swap over with no issues.

Re: 305V6 differences
 

If you change out your wheels, I would be interested in the hub caps.
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Re: 305V6 differences
 

Appears to have the original optional heavy duty multi piece 17" rims. Truck tire shops should have no problem mounting new tires with tubes. The diameter of a 7.50- 17 tire is equivalent the diameter of a 8-19.5 tire. Taller is better on 3/4 tons. Standard ratio of a V6 GMC 3/4 ton is 4.10 compared to standard ratio of a Chevy 3/4 ton at 4.57.