Manual Transmission Swaps

[69GMCLonghorn]

My 1-Ton Longhorn has a somewhat built 350 and an SM465 4-speed. Great set up, but I'm tired of taching at 3100 at 70 MPH, especially with good old So Cal gas now hitting over $3.25 a gallon!!! I'd like to get a 6-speed truck tranny, but I'm seeing that they are major bucks and hard to come by in "used" fashion. So now for the questions:

1) What tranny should I be looking for?
2) What will need to be done beyond using a different cross member and bell housing?
3) What about the clutch? Can I stay with a dry clutch?
4) Speedo hook up: Is there any way to use the factory speedo or will I be looking at installing a "race me" speedo?
5) Any other advise?

By the way, if anybody is thinking of responding by saying, "INSTALL AN AUTOMATIC", please save your breath. It's a truck, not a Cadillac.

[snj8198]

By all means, go with the nv4500! The NV4500 is a constant mesh, fully synchro'ed, top loader that is as tough as the sm465, has a closer 1st/2nd gear set than the sm465 and has a .73 overdrive. You didn't say anyhting about a transfer case so I guess this is a 2wheel drive?? Advanced Adapters has a custom bellhouseing with the clutch fork opening on the driver's side, that will allow you to use your mechanical clutch. AA also has the trans mount to let you use your stock cross member.
I'm not sure about the stock speedo cable. The port for this is on the passanger side though. I used an elecronic sending unit for my Ultra Lites.
Check the junk yards, these transmissions are popping up quite frequently.