IanJK46conv

is it possible to swap a 5 speed trans out of a 99-04 gt for a 6 speed? any reason to do so?

nanaki

mmmm... t56 swap is hot. there's no reason to unless you plan on running some mean power or you find an awesome deal on one cause your stock one broke[&:]

IanJK46conv

yeah sounds cool.. original, no?? haven't seen much of that, maybe i'm not looking hard enough. better gas mileage with the 6th gear?

mills281e

Not a bad idea if you're doing a ton of highway driving. I rarely use sixth and I don't think the gear ratio is all that much different than 5th (in even my own gear box), or 5th in a 5-speed such as yours.

For the road course guys....may just add to pulling back or pushing into the wrong gear (due to the pattern being tighter) until they get really, really use to it.

2000GT4.6

There is a sticky about this swap in 4.6L tech. Links there for gear ratios etc.

Generally speaking, unless you get a viper spec there is little gain. With the regular Fbody 56 you get something like a .75 5th and .58 6th, which means you would have the same final gear now, but just have an extra gear between 4th and 5th. The only real advantage to this would be racing above about 120 MPH (depending on you axle ratio).

WIth the viper spec you get a 5th gear that is nearly identical to your current 5th, and an even longer overdrive 6th gear. This would allow you to run a shorter gear ratio in the rearend (re more agressive) and still not have bad highway RPM.

Subotai_95

It's possible yes, but as 2000GT4.6 said, there really isn't a need for it unless you're going to be putting some really mean power on the road at some decent speeds.. You'd also probably need a new flywheel, throw-out bearing, bell housing, slip yoke for the tranny, new cross-member, and a new drive-shaft also.. I'm not sure that you'd need a new clutch, but I'd look into it just in case.. I looked into doing this with the mach when I couldn't decide which direction I wanted to take it (road-course vs. drag), and it's not a bad set up, just not the direction I ended up deciding to go.. If you stay with an M5, Tremec makes good tranny's in the TKO-500/600.. All depends on what you end up wanting to do..