John,

The second "D" is for the symmetric spool.  Not required on the 235-360, but makes assembly easier. 

Chris

"Thanks Paul, that's useful information. I'm pretty sure the part number is incorrect, though; I think it should be 108AMS32-DLB (not D)-3V-14-08-Y. There is no "LD" code listed in the Oildyne manual, but "LB" designates "Reversible locking with Back Pressure", which I think is what people are using these days. Perhaps if Sam's part number was read over the phone, the B was understood as D?"