What is the diff? W 56, R150, 151
 

I have a 93 a/t and planning on doing a m/t swap. I have found some info about these transmissions but I am stumped as to the details about them. What are the differences and similarities? Which one should I be looking for?

Also, There is someone local who has a m/t (don't know what type yet) from a 4 cyl but he says I would need a bell housing for a 6 cyl for it to work with my truck. Then I read a post about a guy who did a a/t to m/t swap and he did not need to replace the bell housing at all. Can anyone who knows what they are talking about shed light on this subject?

Try here:
http://www.4x4wire.com/toyota/faq/parts/
and here:
http://www.marlincrawler.com/htm/transmission/hilux.htm

Hmm.. I did look previously at Marlin site but somehow missed that information. Thanks.

I believe this means that the R150F is the most compatible 5 speed with the 93 3.0. What about gear ratio?
"We can rebuild the stock 3.83 first gear with a 4.31 first gear from a R151F turbo tranny
First gear ratio is 13% lower than stock ratio (4.31 vs. 3.83).
Cost $385."
Does this mean more tourque or lower end tourque? (Or maybe it has nothing to do with tourque at all) What I'm asking is, what would I experience with a 13% lower gear ratio than stock?

More torque and higher engine rpm's in first gear, easier to start moving from a dead stop, especially on an uphill or while towing.

If you have a V6, you can only put a 150 or 151 behind your engine. There is no bellhousing to adapt a W56/G52 to your engine. There is a bellhousing to adapt a 150/151 to a 22rx engine that came factory behind the 22ret.

The 151 is Toyota's best tranny, IMHO. Lower first gear, 23 spline, no adapter needed to mate to a 4-cyl, gear driven tcase.

Also, I wouldn't believe that bit about not replacing the bellhousing.
The bellhousing for a manual if different, it has to have provision for the clutch for example.
I suspect what he said was that he didn't swap bellhousings from one trans to the other - he probably took out the auto w/bellhousing and put in the manual w/bellhousing.

Yes that would make more sense. You have answered my questions.