280SL 1969 starter mount bolt

[clunker]

I seem to be missing this rear mount bolt (shown is pic shamelessly lifted off an auction) the mounts through transmission housing rim. I have the same original old heavy style starter with the additional front mount bracket. I assume other rear mount bolt, accessed from transmission tunnel is there, so it is mounted securely front and back. However I want to replace with more powerful / lighter SR59X which will just use the (later) two rear bolt mounting.

Can anyone advise what size is this missing bolt and nut?

Thanks.

1969 280SL 4-speed US spec.

[kampala]

The information is contained within our Tech Manual under the "starter" section.   

Here's the specific excerpt about the bolt, but see the Starter section to confirm we are referring to the same item.   Best of luck.

"Bolt, nut, washer & lock washers – If your existing starter has two allen bolts and thread directly into the starter (both top and bottom bolts) than you will need to have one 10mm x 90mm bolt, washers and lock washers on hand for the bottom attachment. The new starter does not have threads on the bottom attachment and requires a bolt/nut/washers. Later pagodas may already have this bolt on their old starters."


Link to tech manual "starter" :
https://www.sl113.org/wiki/Electrical/Starter

[clunker]

Thanks!
Dang, I read that section of the tech manual carefully too (I thought) and totally missed it!