Re: 351 V6 swap to 478 V6
 

I have the service manual from 1969, 4000 thru 6500 series GMC trucks
this bus is listed as a SM-5500M and the engine listed is the 305C as standard and the 351C as option
305C with 435GL transmission
351C with one of three transmissions 435GD, 540GD and 540GL as options
i am sure GMC had it's reasons but why did they put a 180 hp motor in this size chassis when the 351M or bigger would work much better
this 351C would be a great motor for a pickup with 4 wheel drive
if i can find a V6 with more hp at a decent price i would do a swap