My rifle has two existing holes for sling studs in the stock that are 2.75" ctc. I am looking for a rail section with the pre-drill mounting holes that have the same dimensions and a rail length of 4.7" or less
Check this out:
https://www.amazon.com/Higoo-Picatinny-Sling-Swivel-Adapter/dp/B01ELCCB4K
I don't know the dimensions, however, I use it for sling and bipod mounting.
Isn't the OBS31132 just what you want?