i got a 92 rs with a 305 an the 700r4 trans . not sure the rear gear ratio
what shoulkd my rpm's be in od at 70 mph ?

 

It all depends on your rear gears, and rear tire diameter. What is it showing now? Does your tach seem to be reading ridiculously high? Faulty reading tachometers on the 90-92 f-bodies is very common. Mine read about double, so I got to practice my math skills while driving!

 

it'a around 2750 rpm's ,not sure of the gears the tires in the back are 255/70/15 . thats what was on it when i bought it

 

That sounds on the high side. I have a built 700R4 with functioning OD and Lockup, 3.42 gears, and 235/65/15" tires. I run between 2300 and 2500 RPM's at 70mph.

Next time you drive it, go to an area where you have plenty of room to accelerate to about 45-50 mph slowly. Count the shifts, there should be a clear 1-2 shift, 2-3 shift, 3-4 shift, then you should feel the TCC lock and the tach should drop about 300 RPM's.

 

Your tires are pretty tall at 28.9".
2,750 rpm, with 4.56 rear gears, in overdrive, would put you at 74 mph.
2,750 rpm, with 3.36 rear gears, in third gear, would put you right at 70 mph.
Either someone did put in 4.56 gears...woof!
or...your transmission isn't going into overdrive (staying in third).
or...your tachometer is lying to you.

 

ok thanks for the info , the guys that had it before me instead of lowering it to get rid of wheel gap they put bigger tires on it .lol
i'm changing wheels an tires this spring an lowering it some
the tack might be wrong cause it idols at like 1100-1200 after it warms up
i want a tack with the rev limiter in it anyway .
it's got 147000 miles i'm sure it's been abused some , but i want to fix back up nice ya know nice an fast .lol