The first tranny is a world-class t-5.

Look for some casting numbers on the main box, a green and white sticker or an aluminum tag. The most useful would be the sticker or tag. What you are looking for is the first four numbers, if they are 1352, its a T-5. If you've got a tag or sticker, the next numbers will help you decode what it was used in and what gear ratios it has.

That first tranny has a 'short throw shifter' mounted in place of the stock shifter. Those things sell used on e-bay for about $75 and new closer to $200.

Run it through the gears and pop the cover on the box and have a look at the syncros and fluid to see what sort of shape its in!

By the way, it looks like its got a ten spline input shaft from a jeep, which might work just fine with your stock clutch.

'51 Chevy 1/2 ton w/'62 261, HEI, offy, fentons, dual carter/webbers, t-5 & 12 bolt posi