Ok my 89 camaro RS runs at 3500 rpm's in 5th gear going 60 mph what gears do u think that i have. I dont think that they are stock but may be. It has a 305 LO3 5 L & 5-speed trans.

I forgot it also gets around 21 mpg in the city so this doesnt seem right to me does it you?

Thanx

to really calculate the gear, we would have to know your tire size, and you 5th gear ratio.

but on an rpm calc i used, i had to punch in 14" wheels, and a 1:1 trans ratio with a 4.56 rearend to get 3500 rpms @ 60mph. overdrive and larger wheels would only lower the rpms. sounds like you've got a monster, or you have it in third by mistake. i cant understand the mileage.

you can support the rearend on jackstands and spin the driveshaft to figure it out pretty close.

if it is posi, lift both wheels, mark a tire and the driveshaft, and count the number of turns the shaft makes to spin the wheel once. that is your ratio.

if it is non-posi, lift one wheel, do the same procedure, but double the result.

or you could take the cover off and count the teeth, or look for a stamp.

the high rpms in overdrive and the high gas mileage dont seem to add up. is it high revving in all gears? maybe the tach is off?

I am pretty sure that the tach isnt off but who knows. And thanx for the help i have the stock rims with 235 60 15. But it seems like it needs a 6th gear. Because it is revs alot and you can tell going down the interstate.

Either your tach is screwed up or you have a 6:1 gear.