2 different #4 drives, and #4 experts ?
 

Ok just got 2 different #4 drives. The old drives had a bolted rectangular plate bolted under the upper drive shaft that encorporated the fluid resevoir plug in . The new drive , has the fluid resevoir plug in and then an opening under where it looks like a plate should go the shape of a lower case letter H . Is something missing or did the casting just change. I think something is missing because the aluminum is not painted in this cavity in the casting. Sorry no pictures.Old drives had small shafts the new ones have large shafts .
The numbers on the casing are as follows :

D456117 0
11/17/890w3550 RH XS

B455314 0
S 2188 LH XS

Does this mean anything ?