I have an 88 silverado 1500. The transmission went out and I had the 305 engine and transmission from 83 Scottsdale which is now in the truck. I am mechanically inclined and have always done my own work, just want to make sure I have all the info so I can do it right I have all my dash working and I have bumped it to make sure ignition is right.

Questions:

1) is there a swap manual, all i can find is for the other way 305 to 350 and ive been told you can't just reverse process.

2) the 305 has a fuel pump on it but there is a fuel pump already in the tank, can i just hook fuel line up or do i have to do I have eliminate one, if so I would prefer to use the pump that is at the tank.

2) is there anything I have go do to wiring harness or sensors.. pretty much anything electrical.

 

1) Find a Chevy truck forum.

2) Ask your questions there.

3) Follow their advice.

 

It doesn't matter if you were trying to replace your sbc 350 with a sbc 262, 265, 283, 302, 305, 307, 327, 350 or 400. Dimensionally they are all the same. There may be a few gotchas that you need to be aware of but let's just point out a few things between '83 and '88.

Are you keeping the TBI? Your '88 intake while it can be made to work, be advised that the center four bolts on the intake is at a different angle as the '83. I'm not one to be elongating holes and filling it with rtv so that decision is on you or you could use an TBI to carb intake adapter. The 350 uses a larger 61#hr injectors as compared to a 305 54#hr and may cause a rich condition. Due to the different bore size between the 2 engines, the knock sensor as well as the ESC module is specific to the bore size. This is moot as you're using everything from the '83s transmission but be advised that the early block has a 2 piece rear main seal vs the later 1 piece which you want to match the flexplate to the respective block. '83 v-belt vs. '88 serpentine use a different rotation water pump.

TV cable adjustment and geometry is super critical on these transmissions so make sure you have the correct brackets and adjust tension accordingly.

Is the speedometer connection on the '83 same as the '88? I'm thinking older models use plastic gears and a cable drive whereas the later trans uses a tone wheel with a mag VSS. Not sure '88 might be the cutoff year when they switched. You might hafta swap parts from the '88 trans to the '83.

As for the fuel pump, remove fuel pump and rod off the 305. Cover the hole with the 350 fuel pump block off plate.

Electrical connections/wiring...everything that plugged in to the 350, I would make available on the 305.