70 MGB GT - Odometer Alternatives

[Gary Davis <GDAVIS@ibr6gw80.gp.usbr.gov>]

Greetings All . . . .

When I purchased my car last February, it was advertised as having
less than 60,000 miles on the odometer.  That's true.  The problem is - I
have an OD speedo and no OD.  So, I can only assume the original
speedo was replaced some time in the past and that the odometer is not
giving me an accurate reflection of actual mileage.  

If that's the case, does anyone know of an alternative method for
estimating how many miles the car has endured?

TIA

Gary Davis