i know its probably not good for my engine, but i had 2 400lb wood stoves in the back and i had a friend with me and showing of the torque i had going up the hill was cool

 

i have a c6 that has a granny gear but im afraid to use because i think im going to brake something. it feels and sounds like im driving a semi truck or something

 

It isn't a bad thing that you were in second, but the gas mileage sure was hurting.
Normally if you floor it you shift to third at about 65MPH any way, but I bet the RPMs where high doing 60 in second.

 

Unless those tires are more than 24 years old, they are metric

What code is stamped on the data plate underneath the word Axle.

 

I have some tires that are a few months old and they aren't metric.

 

i just found out by a fte member i have 3.73 gears

 

I don't know if this forum generally prefers new threads for similar questions or piggybacking off of older threads, like this one.... I can start a new one thread if you prefer.
Basically my speedo is screwed. I took it on the freeway a couple weeks ago for the first time and the speedo was wrapping past 100 and I was barely keeping up with traffic (I'd guess the avg speed was 65-70). The guy I bought the truck from is about the 4th owner and didn't know much about its history (his son drove it for 5 years with apparently NO maintenance done) so I have no idea if the axle gears were replaced, what tranny it has, etc. Is there any way I can get this thing to read approximately correct so I don't get a ticket?
I'm mechanically inclined and I'm not afraid to get dirty or turn a wrench (I replaced the rag joint on this bad boy in about 1.5 hours and I do all my mechanic work on my racing car) so advise away.

Thanks in advance!

 

Transmssion ...automatic or standard ?

There are many ways to get close to the idea of the ratio of the rear end but the best no fault method is to remove the rear end and counts the splines or the pinion gear & Ring gear ....and then do the math.

There may be a rear axle tag attached to one of the differential studs/nut.
You can turn the wheels 10 times and count the number of times the driveshaft turns

The info you need once have verified the Trans/ axle ratio / tire size. All the info you need is linked to in post #2.
Just click those links to view.