Once again, not a K5 but a full size......

I have a 1998 C1500 LWB 4.3L Automatic with 57,000 miles. The motor in my truck is acting up and I am thinking about replacing it as the rest of the truck is in near show room condition. My question is, what all would I need in order to put a 5.7 truck engine in it? I also have a 3.08 rear end and would like a 3.73 auto-locking. I would much rather sink some money into my truck than buy another truck. I am not sure if I would need a new transmission or not RPO Code M30 which I believe is the 4l60E (mine is in perfect condition). Please let me know what all would be involved in putting a crate truck engine in in place of the 4.3L. I am not looking for a hot rod, just a truck engine. Thanks in advance guys!

 

find a wrecked donor truck of the same vintage. i think your truck was the same (under the hood) up to/including '94.

you'll need to swap out the wiring harness, ECM, maybe even the fuel pump (can't remember what the spec's between the 4.3 & 5.7 are off hand). your trans will bolt up fine, but might need to be "tweaked" to run 100% with the 5.7