01T, cannot be 71, will be 17 (271)-B

Could be just 01T-B.

If 8 was marked on DRIVEN gear, it would have nothing to do with DRIVE gear teeth, because what DRIVE/DRIVEN gears truck has, depends on trans type, rear axle ratio and original bias ply tire sizes.

1964 F100 2WD 3.70-1 4 M/T 7.00-15 tires: B9C-17285-A 7T DRIVE gear / 01T-17271-B 19T DRIVEN gear

1964 F250 2WD 4.56-1 4 M/T 6.50-16 tires: 01T-17285-B 6T DRIVE gear / 01T-17271-B 19T DRIVEN gear.

How many more examples would'ja like? There are pages of like examples for F100/350's, P350/500's, F500/600's and etc etc etc!