Gear Ratio Conundrum

[Deleted member 21429]

Hey all, I have a problem to figure out and hope someone out there may know the answer. Here goes
Bought a Step Van
The frame, engine, transmission, and rear end were assembled by International Harvester Nov 1972 and then shipped to the Olson Corporation who put the body on it according to whatever the customer ordered Feb 1973.
It has an International 5.7ltr 345 V8 with a Chrysler 727 turboflight 3 speed automatic transmission and a Dana rear end with dual rear tires.
It was bought/ordered by a Fire Dept, then it was a NH state Police Paddy Wagon with a steel angle iron cage welded in it.
Then it was bought by a logger.
The logger put new leaf springs, a lift kit, new shocks, stabalizer, and 33 inch all terrain mudders on it. Looks great! Has only 50 miles on it, perfect. except.

He never changed the gears in the rear so the speedometer is off and the tranny is confused and cannot find overdrive and the trannys rear seal has a drip.

I know that I am to take the current tire size times the ratio divided by the old tire size to get the new ratio.

Problem is I do not know the old tire size and have no way of knowing for certain.

The Stepvan is an Int 1210MSC which means Multi Stop Cargo and was never geared for speed.

Does anyone out there know what gear ratio I should order so I can at least go 70 vs 50 for top speed?
Any help would be appreciated because I drove it 320 miles to get it here and I don't want to drive it like that although the logger did till he retired. It has 16 inch rims with 8 lugs.
Thanks, ~ peace

 

[creature]

do you have a tach?

 

[Deleted member 21429]

@creature No I do not have a tach. Am planning to install one though.

 

[Coywolf]

http://www.automobile-catalog.com/tire/1972/1246055/international_scout_ii_4x4_6-232_4-speed.html

http://www.how-to-build-hotrods.com/gear-ratio.html

You are going to have to buy smaller gears in order to gain high end, however, you will lose alot of torque, I think. I could be wrong.

It's a crap shoot, really. You will just have to play around with different gear set ups.

The only vehicle like that that I could find on the interweb is a Scout/scout 2.

I'd also recommend taking it to a transmission shop and asking how much they would charge to determine why gears you would need.

 

[Deleted member 21429]

@Coywolf I agree . I am planning to get the gearing, that is definite. Was thinking about a trans shop a couple of days ago and will most likely do so. Just double checking and triple checking before I plop down what's looking like 7-9 hundred bucks. Thanks for the input, I'll check out the link. ~ peace and I have not had a vehicle in over 10 years so I have all the time I need to do this right. The thing is in great shape. Solid and runs well. Fun to drive.