Originally Posted by Kawabuggy
The only externally balanced engine I can think of off the top of my head is a 400 small block. Did one of these vehicles have a 400 small block in it? If so, that flywheel WILL NOT work with an internally balanced engine such as the 305, 350, 327, 307, 327, etc;
As mentioned above, there are two flywheel tooth counts 153 or 168. Match the starter to the flywheel and your problem will be solved. If you have a 153 tooth flywheel. Look for a starter from a 1970 Olds product with a 455. It will be a high torque starter designed for the 153 tooth flywheel and will bolt directly to your small block.
Or, go with one of the gear reduction starters off like a 95 Chevy 1/2 ton pick up with a 350. That starter will be VERY light, will pack one hell of an electrical punch, and will start an engine even if the battery is weak as it draws less amperage than the old style starters. It is also designed to work with a 153 tooth flywheel.
If you need a 168 tooth starter, buy one for a '69 Camaro with a 350.
olds starters mount on the left side of the block, not the right side like chevy.
also, i do trans R&R for a living and have never seen a 153 tooth flexplate (OEM) on any 86 and newer chevy engine for a truck.
to the OP, if the tooth count was the same, then why would you change the starter? did the truck start correctly before? have you tested the starter off of the donor truck to verify that its even good?
have you tried the starter (the origional starter you had on the truck) that you took off your truck to confirm that its a flywheel problem and not a starter issue?
and lastly, have you pulled the starter drive into the start position to verify that the starter teeth are meshing properly with the flywheel? is there a gap?