Help With Starter Motor Part Number

[mrein3]

Help.
I need to replace my starter motor. I saved a thread from a few years ago that stated ACDelco Gold 337-1011 Starter for $80.97 on the jungle website is the starter to get.
However, the amazonconfirmedfit tools says "! This does not fit" your 1971 K10 Pickup"
So I change it to 1972 Chevelle 307 which is the engine currently residing in my pickup. It too says "! This does not fit".
So I change it to 1971 Chevelle 307 and you guessed it, "! This does not fit"

The jungle website suggests another ACDelco Gold new starter, 336-1860.
When I go to Rockauto and click my way to starter for all three above vehicles they all say 3361860.

The only difference I can see in the pictures is the two starter mounting bolts on 336-1860 are one long and one short where the 337-1011 has the two mounting bolts both the same length.

So I rolled under my truck and took a picture of what has worked on the 350 (not original) that was in the truck when I bought it, the 383 I had in there for about 10 years, and the 307 that is in there now. It has the two, same length starter mounting bolts. See pics.

So do I order the 337-1011 which appears to be a direct replacement to what I have now or get the 336-1860 that Amazon and Rockauto both say is stock for all three applications and then screw around for three weeks getting the correct length bolt for that shorter side?

No comments on the oil dripping on the starter. You'd leak too if you were a small block and in your third vehicle.