Best olds 350 starter

I purchased a Powermaster 9510 for my 455 15-20 yrs ago. Works good

Robbmc starters hands down
Clears headers and manifold and you can clock it anyway you want

Depends...

Hi Compression? Lo Compression?

Both previous mentions are good starters. No doubt. The Robbmc's are cool in the fact that the starter is pretty much the same, but the nose mounting "plates" can be swapped out if you use it on something else. And they're not super-expensive, although a bit pricier than most. And most of those mini-starters give you better room if you're doing headers or need extra clearance.

If it's mostly stock, up to say, 10:1 or so, you can get by with a good, rebuilt ACDelco/GM unit (I'm talking about old school Delco reman, not some crap hack from Autozone). You can also get a unit from a 455 hi comp engine and use it for a mildly built hi compression 355.

The problem is actually finding a good, stock unit. I'm just putting it out there as not to poo poo on the stock Delco starters because it came from the factory. They made a zillion of them and if it will spin a 455 hi compression engine, it'll spin your 355. All those millions of cars GM built back then cranked over with a Delco starter.

The quickest way to tell the difference between a hi-torque and regular Delco starter is to look for the spacer/tab for the stator windings. If it's further away from the solenoid in the front with about 3/4" spacer, that's a hi-torque unit. If closer to the solenoid, it's a "regular" starter. Pic below shows regular starter on the left, hi-torque unit on the right.



And say if you run up on a Chevy hi-torque starter, don't despair. If you're mechanically minded, you can always swap the business end housings to the Olds style. It's not as hard as people want to think it is. It will take a bit of disassembly of the unit, but hey, it's a good time to go through it, clean it, repair stuff as necessary, lube it, and make sure it's operating at peak efficiency.

I went with this one, super compact, even smaller than the 9510. I had to trim the electrical connection studs to clear my current headers. I think moving the tube to clear the mount caused my issue.