Sounds more like a 4.10 gear, with about ~300rpm of converter slip.

If you have a high RPM stall converter though, it could be 3.73 with 550rpm of converter slip... hope you have a big trans cooler if that's the case.

Don't forget to allow for converter slippage. However, what the OP has for RPM vs. MPH would = excessive slippage. I am with you, needs to take it somewhere and have the speedometer certified.

im not 100% sure about the gearing. and the speedo was used with a GPS. i just got the motor in and just need to work out a few bugs is all. I'll get er' right.

im runnin 3.55's and a 215/75 rear tire and im around 70 at 3k, 2700 is about 60-65. And as far as getting off the line, the straight tracks are mine from nearly 2 weeks prior to the picture. 213 feet and I just stabbed it on green.http://img.tapatalk.com/d/12/09/17/a3ene3u4.jpghttp://img.tapatalk.com/d/12/09/17/4u9a3a7e.jpg