Technical Banjo rear end ratios

I am currently rebuilding a 40 Ford banjo rear end for a guy which will be fitted with a Hailbrand 201 centre section, everything came to me in pieces with a selection of various carriers, axles and ring gears and pinions. One of the ring gear and pinion he provided to me he believed to be a match set with both gears being in good condition which he wants to use.
However after stripping and cleaning the gears I find the ring gear is stamped 37-9 and the pinion is stamped 11-39.
37-9 would make it 4.11 ratio and 11-39 would be 3.54 ratio.
My question is can you mate the 37 tooth ring gear with the 11 tooth pinion making the ratio 3.36 or will this be a miss match of gears causing problems ??
He has supplied me with some 9 teeth pinions and 34 teeth ring gears so I could put together 3.78 ratio and 4.11 ratio gear sets.
Thanks in advance for all info/advise given.

 

Opps sorry meant to post this in Traditional hot rods not customs.

 

Bump.
-Dave

 

I've never seen any marked --/ 39. Only 9 ??

 

You cannot mix different ratio pinions with different ratio ring gears and expect a good result. 11-39 is 3.54. 9-34 is 3.78. 9-37 is 4.11. 3.78 and 4.11 pinions use the same number of teeth but have a different helix angle. You need to check the numbers to make sure you use a matched set. As you can see, the number is stamped on the end of the pinion. In this case it is 651. They are usually 4 digit numbers. The corresponding number will be engraved on the back side of the ring gear. It can be hard to see though.

 

More than 50 years ago, as a college student, I changed JUST THE RING GEAR in my '47 Ford sedan (went from 4.11 to 3.78 or 9.37 to 9.34) in an attempt to improve the gas mileage. I actually drove it from my home in central Massachusetts to Providence, RI, about 90 miles, before everything came apart. I found another 3.78 complete rear axle in the garage of a friend's apartment and made the switch. Drove it to NYC after that.

 

Thanks guys I thought this would be the case, I will check all the other pinions and ring gears he has provided to see if I can find a match set. If not has anyone tried the new sets that Macs sell are they good quality not China rubbish ???

 

If you look real close, there are numbers ETCHED on both the ring gear and the pinon. These were put there at the factory to match the gears. I always try to keep them together.

 

Thanks for all the info guys, have now managed to find a matching set.