Yup! The gear ratios between 4 n 5 speeds (truck trannies) are not all that different. Just think of 5th gear as overdrive...
On the other hand if you opt for the W58 celica tranny you will feel a difference as it has slightly taller gear ratios especially 5th gear! You'll be doing 80+ with ease...

 

Well if you put a 5speed in your truck and retain the 307 gear ratio you will probably have more pressure put on your clutch, and crank, considering the lower rpm's.

 

that is bad or wut? im not very thorough with transmissions n stuff... how much wuld the 308 gearing cost? and by pressure u mean strain on my clutch right?

 

yeah pressure on your clutch. If you are in the salvage yard you might as well pick up 4x4 center section as well.

 

I just changed the clutch on my truck, 4 speed. when i bleed my clutch slave cylinder, the pedal felt a bit sluchy. not as much pressure as it should have. I changed my clutch cylender too. whats a quick fix for this?

im also thinking of doing this 5 speed swamp. i heard there aint much diffrence but the overdrive.
meaning ill save gas or what?lol..

and when hows that 8 supra LSD work? what year does it have to be from and what are the pro's from going this route..

 

LSD > Open Diff....
i think the MK3 turbo and MK4;s have 8" rear ends. you swap the internals, not the diff cases.

 

thanks.. i would be able to weld that diff, right?

 

that would kind of defeat the purpose of the lsd. if you want the axle locked all the time just weld the spiders on your current diff.

if you don't want the weird quarks that come with a locked rear i'd say go with the supra lsd.

 

ok so... the supra MKIII rearend swap only works if you have the V6 8" rear end heres a really good write up on it

http://4x4wire.com/toyota/tech/supra_lsd/