The time has come to replace my 5.7 vortec motor. After 295,000 miles, the valves are giving me issues and I'm going to install a new motor. Looking to swap it out with a remanufactured engine. have a few questions.

1. Does the 3500 use a two or four bolt main.
2. Been reading that the timing cover can't be reused? Is this correct?
3. Not sure of the fuel injection system. Read there is a newer version to replace the spider web system, that may be currently installed. Is this a good decision? Does it require a different wiring harness or cause problems with the ecu?

Any advice would be helpful.

Thanks,

 

Find a used vortec and all should be the same. If you want to open up the intake and change the poppet valves to the new spider injector setup great. It might not be needed however.
I wouldn't try swapping an older version of the 350 as there are a lot of differences with the vortecs

 

Two or four bolt main does not matter with the four bolt being more durable in severe duty applications. For ease of install replace with the exact same (year) motor that way you don't spend days running around searching for or waiting for a part.

From experience there are often small changes in accessories, brackets, sensors, etc... during the run of a body style. Best of luck.