[Xoloski]

Hi, I have a 1978 D100 Custom with a 3.7 liter & 3 speed trans.
My starter drive (Bendix) has failed and I am having a real hard time locating a new one.
O have purchased 3 new drives off Ebay and none of them fit because the spiral teeth stamped into the drive are a different angle than the original and the teeth do not engage with the starter drive shaft. Local parts stores have nothing, even the guy at NAPA said he has no starter drives for my application.
The photo shows the difference in the drive tooth angles. I even opened up a core starter that I had sitting around and it has the same angle as mine and a bad Bendix.
Can anybody offer a part number for this drive with less angle than the other, or shed some light on when the angle change happened?

These are the photos I used to request a refund for the part that didn't fit, thus the text.

 

[ImperialCrown]

Welcome to Allpar. Someone may have put a different starter in this truck at one time? This can cause a wrong part to be looked up. You may have to order by description?
Conventional practice is to exchange the starter for a reman assembly instead of replacing individual parts.
They figure that if the Bendix is worn, the brushes and bearings aren't for behind.

The big chain auto parts stores are pretty useless when looking for old parts. They just go by what their computer says is available.
These are NOS (New Old Stock) parts. They are already about 40 years old. Depending on how carefully they were stored, they may be starting to rust and the grease beginning to thicken.

The most helpful to me are the 'mom &pop' auto parts stores. The have the paper part catalogs in the back room for cars that are older than me. A part number listing is the biggest help for old vehicle parts shopping on the internet.
Your Bendix looks more like a (Standard Motor Products) SDN21 (N/A) than the one which it calls for, which is the SDN22:

 

[Xoloski]

ImperialCrown,
Thank you for your response. I believe that you are correct regarding the appropriate part number for this application and about someone replacing the starter with a different year/model/version. I do know that I am the second owner of this truck and the maintenance it received was not the best. "Pinky", a native of Tombstone, AZ was the original owner. He ran water in the coolant system, painted the wheels with white house paint because he didn't like them factory black, and pulled the timing set when the engine wouldn't start, thinking it was a broken chain. The truck was left like that after his passing since 2001. I cleaned up the front of the crank, installed a new timing set, found the real problem of a stripped nylon distributor gear.
I rebuilt the oil pump, distributor, carburetor, alternator, and starter without changing the Bendix. The truck ran great except for the starter which would clash with the new ring gear. The only reason I didn't replace the Bendix was that I couldn't find the right one and it didn't seem that bad. I couldn't find anyone knowledgeable enough about the part numbers to aid me. My neighborhood machinist Dave, at Precision Machine in Huachuca, AZ 85616 did say there were two versions but couldn't offer a correct part number, he did provide SDN22, the part with the greater angle than the SDN21 you provided, and C212, which I couldn't find.
Anyhow, I like to keep things as stock as possible and am not opposed to rebuilding components like I was trained to do in automotive tech school in 1975. I didn't work as a mechanic in my career but I've always liked applying my skills. Thanks again for your help.
There are a number of good mechanics in my neighborhood. I am two blocks away from both Terry and Bob Woods (of the Sox & Martin era), Chip Porter who balanced engines for Keith Black and drivelines for Jr. Johnson is 20 miles away. And, a newfound friend Larry, also 20 away showed me his 1958 Watson Indy 500 car recently.

The car has a 4 cylinder fuel injected Offenhauser engine and 2 speed manual trans, capable of reaching 180mph on the track. That's me in the background.

Larry also owns this 1951 Cunningham CR2 that has is Chrysler Hemi powered.

 

[Xoloski]

ImperialCrown,
Your excellent answer brings another question to bare. While in the midst of the starter drive quandary, I disassembled two core starters that I have with my (waiting for a project) 440 engine & trans. One of the starters had its 4 shoes like the one from the '78, the other had something I had not seen before. Of the 4 shoes, 3 were connected in series with a high ampacity bus and the 4th, also connected to this bus had a very small gauge wire, about 20 gauge, connecting it with another smaller lead coming from it.
The only logical thought is that the second starter was built for a much smaller or lower compression engine.

 

[ImperialCrown]

There were 4 starters offered. 2 of the offerings shared the the same parts column.
There were 2 different Bendix (clutches) offered. 2 of the starters used the same clutch. One did not.
Dimensionally, the 2 clutches were same size.
I remember the big engines went to a 1.8 hp starter.
The 2 solid copper wires are shown on the solenoid. Perhaps that 4th field was used as a series shunt during cranking?