Hello looking to see if anyone has any experience or advice as to what Electric Starter May fit an R2 Gasoline Powered Tractor, SN 4J321. The Tractor has provision for the Starter, with a 3 Bolt SAE Mount, and STRAIGHT Cut Gear Flywheel. It did not have any electrics on it from Factory that I can tell, but it does have the spot for the Starter. I have looked through old forums, and do see this topic being discussed over the years, but nothing pertaining to something that may fit off the shelf, and not being obsolete. Thank You In Advance.

I don't have specifics but I do have some info.
I don't know the Delco number for the R-2 original starter but may be the same as the R4 which uses the Delco 737-V starter. This is an early 10MT starter, clockwise with a 10 tooth pinion. Depending on how much room you have you might look into the current Delco 39MT 12v gear reduction starter which can be had in SAE #3 configuration which also controls engagement depth. Also can be had in 10 tooth straight gear drive. Would appreciate any feed back as to how this might work out if you go that route.

The R2 and R4 starters appear to be different, the part numbers are different with no interchange and the parts catalog drawings are different.

Cat part number is 6B0286 which translates to Delco Remy 1107426. Numerical part records shows only application as 4J, 6J R2 tractors and 8M, 2R graders. Parts books have NO parts breakdown for this starter. Ring gear 124 tooth. So a rather uncommon Cat application.

Delco 1107426 uses the same starter drive #1850844 as the R4 Starter. The drive end housing is different being a #1878037. Still appears to be a SAE #3 housing pattern so there is a chance the later starter will work if you have the room.
Need to clarify....you state it is a 3-bolt SAE mount. Is it a SAE #1 or SAE #3 style mount?

Thank You for your replies....it looks like SAE#1 with an offset judging from what I can see...I have a attached a couple of pictures, and if you look closely you can see the ring gear is quite far over towards the block. Hoping you can see the pictures ok?

That looks to be an SAE #3 mounting. Bolt C-C spacing should be 5".
Assuming that it is an SAE mounting and with a straight tooth flywheel it does allow several options in starters.
 

So Just went to the shop and measured...you are correct 5" C.C. with 1/2" NC mounting holes, pilot looks to measure 3.6" with calipers, and it is Definitely straight cut flywheel. I had a 39MT Starter for another project, which I tried it does mount up, but it has a 12 tooth pinion. Might have to play with pinion sizes to get the right combination.

10 tooth is an option and you should be good to go. Might need the 5/8" to 1/2" bushings for the mounting bolts.

I will keep you posted as to how I make out, Thanks for all your help
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Talk soon