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I think you need to be a bit more specific about which Pinion you have. The part number is stamped on it.
You also need to be aware that the 1938/39 pinion 1A7297 with ROLLER bearing behind the gear has different (metric size) angular contact thrust pair 3MDJT25 = ID 25mm X OD 62mm X wide 25.4mm which has a single inner race and 2 separate outers ---difficult and expensive if you can find one (£45 each).....it has a rear roller 1 1/8" X 2 13/16" X 13/16"
The previous pinion 1A 7239, had double purpose bearing 1 inch X 2.5" X 5/8 with ROLLER 1 1/8" X 2 1/4" X 5/8"
Mar 1935 pinion BP117 had double purpose 1" x 2 1/4" X 5/8" with BALL journal (pinion shaft rear end) 1" X 2.5" X 3/4"
Have a look at the A7 Friends Archive for the spares lists which show different years details.
My late 1938/39 with the roller has a lip at the rear of the torque tube that stops the outer bearing race sliding into the axle casing and there is a peg ended bolt that screws into the torque tube at the front of the bearing to stop it sliding forwards....but there are different methods for different bearings/years/pinion shafts; and the various spacers and bearing houses are different. 
Dennis
Location: NW Devon
