48 gmc engine trans reare conversion

hello everbody i got a old 48 gmc in nd got it running painted it an drove it to michigan with the original drive line torque tube.it ran good but 45 or 50 mph just not anough so i put in a 250 six an a 700r4 with a colarodo rearend think3.42 gears truck doens weigh mutch you guys think iam over geared or will it b alright. or just keep goen an see wht happens. thanks 4 any info skilly

 

I'd have to say to drive it and see how it does before making any changes to what you have.
I don't remember ever figuring out what the rear axle ratio in the Nova rear end is/was under my 48 but I think it's around 3.0 if not in the high 2's With the 250 and three speed the truck was a bit of a slug off the line but happily cruised at 60/70 and got 20mpg on road trips.

 

Had a Silverado with a 4.3/overdrive and 3.42 gears, it was a good daily driver work truck. Totaled with 250,000 on it when a 16 year old decided she wanted a dunkin
donut and did not grant right of way. You should be fine as long as you keep the rear
tire size reasonable. Jim

 

The combination sounds good. As has been said, it is down to tire size. Not too tall, and not too short, and you should be golden.

Remember, the gearing of 3.42:1 in 4th (0.70:1 overdrive) will have comparable top gear performance to about a 2.40:1 with a good old 3-speed, or other non-overdrive transmission.

 

check out, www.oldgmctrucks.com

 

thanks i like hearing tht it might work all i no is its alot a work.skilly. just hooken up the tv cable a piece a work there to.it makes you really happy when somthing comes close to fitting with out mutch fabrication.

 

forgot ta tell u guys iam useing 15 in tirers 225.skilly

 

well it works great cant get the tv cable right but i will locked up at 70 ta 80 shes getten 31 mpg ..an now i can cruise the country.skilly 250 6 700r4 an 3.52 rear 15 225 tiers.o an its still zippy in town