If possible how hard would it be to put a 6 spd tranny behind my 12v?

 

why dont you do a search on that ??

 

I was a stones throw from getting a 5 speed and swapping out the auto because of a bad torque converter, but I got a good deal on a new converter instead.
It's not easy, but is do-able. A donor truck is ideal, because finding the misc. pieces like new pedal assembly, flywheel housing/ bell housing adapter, driveshaft (6spd trans is shorter than auto) and new input/main shaft on transfer case for 4wd can get time consuming and expensive. Realistic costs will be at least $3k (closer to $5k from my experience) even if you get some deals, but like I said, do-able.

 

Yes it is do-able but you would be further again swapping in a 5 speed. You will not be saving any fuel w/ a 6spd compared to a 5spd if that is what you're looking for.
The ratio from 6th gear in the NV5600 and 5th gear in the NV4500 is only .2-.3 of a difference. The difference is the rowing of gears.

All you really need is a pedal assembly, slave/master cylinder, Clutch, flywheel, input on your transfer case, transmission, bellhousing, lengthen/shorten drive-shafts...
And if you go w/ the 13" for the NV4500 (Which uses the NV5600 flywheel), or the NV5600 and clutch assembly you will need the starter spacer.


-Jared

 

If you tow at all a 12v married to a 6spd is a perfect combo. it eliminates teh annoying 3rd gear blues that the nv4500 suffers from.

get a 98+ manual tranny crossmember it has the holes for a 5spd and a 6spd.

you do not need a 6 speed flywheel a 5spd flywheel works but 6spd flywheels are cheap now a days when you buy a whoel clutch kit ect. the starter spacer is $20 from cummins. you'll also need the later style screw on shifter vs the early nv4500 pop on style. the clutch fork and throwout bearing ar e the same on both the nv4500 and 5600.

Bar none best conversion i ever diod yo my old 12v before i sold it, the nv4500 used to last about 150k miles before an OD would fall off or the input would fracture. my nv5600 went to 280k miles before a syncro ot two started scratching in second. I sold the truck with 450k on it and the tranny was rebuilt by the next owner.

i hated 3rd gear in my 12v on the nv4500 that 6spd with the 3/4 split 4th gear was perfect for maintaining speed on long steep grades with a heavy load and not dropping below 50-55 mph third gear used to tach my poor motor out.

do it its not a hard conversion at all. I might have missed it but are you an auto or 5spd already? 5spd already its a super easy conversion, auto not much more to it. different flywheel bolts add a hydraulic clutch assembly and hole in you carpet along with new pedals and you are good to go.

FYI my old 12v started life as a auto. then a 5spd then a 6spd where it stayed . if you are drag racing or in town a 5spd is king but towing 6spd offers better flexibility

 

I say go with a g56 set up forget the nv5600

 

What year did the 6 speed start ?

 

Started in '99.

 

how much do the g56 usually run? because im wanting to do a 6spd swap too.

 

Just what would be involved in changing from the 5 speed to the 6 speed? My truck is a 95 with 93K never had any problems with the 5 speed but the 5th gear nut gives me some concern. I carry a new nut with set screw with me at all times. I am pulling about 9k and pull on the Natchez Trace a lot and the speed limit is 50 mph I either have to drop to a lower gear or do 60 if I ever have a problem with the nv4500 that may be better option if the price difference was not alot. I never thought about upgrading to a dif trans.

 

you dont want the g56 with 4:10 gears

 

If I found a 99 V-10 with six speed would that swap right in my 95 12 v ?

 

yea it should it should most everything would work not sure about the driveshafts tho