If you're installing the trans with the engine...have the vehicle jacked WAY up so there's room for the trans to hang down as the engine is dropped into place.
When it was me, I bought a proper 3-foot long 1/2" drive-to-3/8" drive impact extension. That, and a 3/8" impact swivel socket should make short work of bellhousing bolts in-the-vehicle. If the bellhousing bolts have the extended-stud feature, you'll need a semi-deep impact swivel socket.
35" 1/2"Female-3/8"Male Long Impact Adapter/Extension
sktools.com
The downside is that SK Tools is now owned by the Communist Chinese. Perhaps other companies have a similar item. (Snap-On has a competing product, but it's POORLY DESIGNED. The Snap-On unit is a 3/8 extension with a 1/2" female drive end. The shank is thin, won't transmit impact torque very well. The SK item is a 1/2" drive extension with a 3/8 male square on the end--the shank is much thicker and stiffer.)