That ebay trans is actually a Chrysler trans, Chevy did use them in some of their late '70s 1/2 pickups a vans. Chrysler called them the A833, even though they had a dozen variations with most being non-OD. Do a search and you will find several guys on this forum using one of them.
The Chevy versions have 10 spline input. Most of the Mopars are 23 spline. The one in my '69 Roadrunner has 18 splines with straight cut gears, a longer tail housing and referred to as the Hemi 4spd even though they were also used behind 440's

'67 GMC 3/4 292 4spd