Since I'm going to have to drop my trans (currently the original 4 speed from 1984) I'm considering putting in a 5 speed. Among the things I need to consider are . . .
The cost of a used 5sp trans - plus does it actually increase it's sale value when I sell the truck. What is a "reasonable" price to pay for a used un-rebuilt, 5sp?
Will it really matter, on a strictly street driven truck, which model (aside from a 2x vs. a 4x) of 5sp (W56, L52, G50 etc) I get?
I've read the Ws are the "best" but will that really matter for my situation?

Additional parts such as: a different cross-member (were they different?)

Was the clutch kit different? From searching for clutches already the question whether it was for a 4 or a 5 has not been asked so I presumption at this point is they were not different.

Thank you in advance

 

You buy a rebuilt from marlin. Clutch must fit on spline count and in diameter to the flywheel. Bellhousing must fit
It will not do anything for any resell value. If it is a low mile, ultra clean truck - it would probably hurt value, as the 5speed "does not belong".

Why would you want a 5th gear? you could also regear your third members (differential). You want RPMs down on the highway, install bigger tires.

Marlins site has a gear speed / vehicle speed calculator - you can play with it and figure out what you need.

 

Many factory 4 speed trucks were built with a relatively high differential ratio so that they are able to run moderate engine speeds on the highway in 4th gear. (1 to 1 direct)

This higher diff gearing makes an overdrive 5 speed tranny less useful, except on fairly level terrain and lightly loaded conditions.

Do you know what your diff ratio is?? I've never seen a 5 speed truck with higher than 4.10s,

 

The rear code is G39 which = 3.15 in an 8 inch rear axle. I have no reason to believe the ratio has been changed except . . . when I go up significant hills (like going north out of Phoenix) my engine is screaming in 4th (no tach so just my ear-dyno).

It toned down some once I put some slightly taller (by almost an inch) rear tires on – but it could be better.

Around town I probably wouldn’t use 5th much but between towns and on the highways I imagine it would be useful.