The truck I'm hopin to get is a 6 speed with 3.55s. Should I get fairly good mileage?

 

All depends on the right foot. My G56/12v with 3.55's and 33"tall Ricksons (makes RPM to MPH ratio more similar to a stock tire and 3.23 gears) gets me about 15 in town. Haven't done much highway in the last two years since the G56 has been in it.

 

I rarely tow, and as a daily driver I love my 5-speed NV4500. I find it more fun to drive then my buddies 6-speed. The fluid is expensive, but its not like your changing it often. Just my opinion

 

i have a G56 in my bosses D max truck and I can tell ya that it runs out of rpm real quick .... and it has issues like needin g to be 1 qt over filled or they wont last ( from what I have been reading ) and everyone suggests the redline trans oil in it or else... I have heard issues like the ones listed above to for the nv4500 ... one weakness or another ..... would love to do a rock crusher and a gear vendors .... break this

 

Mines a 5 Speed, not really much of a difference. I've driven them both.

 

shaft size on the 6spd depends on the year of the truck.

99-00.5 NV5600's have the same size input shafts as the NV4500 (1 1/4") with the S.O. motor.
the 01+ NV5600's have the larger 1 3/8" input shaft and the H.O. motor.

the NV5600 is not user serviceable where the NV4500 you could probably rebuild yourself.

everything in the 5600 is press fit and requires special tools and a press to work on, plus very hard to find parts makes it near impossible to work on yourself, however you can get a replacement trans for about $3000... I paid just under $3000 to have mine upgraded/replaced when my small shaft 5600 ripped all its teeth off of 6th gear and broke the intermediate shaft inside. I replaced it with the larger shaft NV5600 and had my clutch hubs swapped out by south bend to fit the larger input shaft.

so you can get the NV5600 replaced, and it is definitely a better trans if you need to tow heavy as it does not have that big rpm gap between 3rd and 4th like the NV4500.

NV5600 is heavy though. weighs 360lbs by itself.

for final drive ratio's they are close, but not the same.

NV4500 final drive ratio is .75
NV5600 final drive ratio is .73

 

Thanks for the input! I got a 5 speed! It has a hot rod vp 44 and the airdog 150 can't handle the IP's flow needed so I got a little bit of work to do on it before she's running good. I almost want to get a normal vp 44 for it.

 

how old is the airdog?

is it a newer one or an older one?? I ask because in recent years airdogs product quality has gone to hell and the newer pumps are suffering from leaking pump seals and steep fuel pressure drops. All of this was unheard of from the older pumps that were make 3+ years ago.

My Airdog150 is 4 years old and keeps up just fine with the fuel demand of a 576hp truck...I only drop 4psi with power turned all the way up. so 16psi WOT 20psi idle.

 

The pump looks 4 years old atleast. It was probably done with the edge juice and attitude (that are discontinued) and it's about 5 years old. The pump melted the fuse in it's harness (the fuse failed to blow ) and the pump made a nasty sound. The kid I got it from said the pump stopped running when you turn the key before starting. I opened up the inspection plate and the gear and insides were clean so it looks as if it's the electrical components that are going haywire. I was thinking maybe the hot rod vp44 was putting strain on the pump and caused it to not last as long. The batteries and a few connections under the hood need a good cleaning. It's a typical farm truck with mods.

 

an older airdog150 can keep up with anything a vp44 can throw at it... sounds like you had other issues like a wire short or something...