Identifying brake booster single diaphram or dual diaphram

[CHRYNY]

Can anyone tell me how to positively identify which brake booster is on my 83 Plymouth Relaint (single or dual diaphram version)? Measurements? I want to order the same one on the car so the old master cylinder lines match up.

[135sohc]

http://www.rockauto.com/catalog/x,carcode,1069039,parttype,1884

Top two.

For the most part the automatic transmissions got the bigger booster. Manuals got the thinner/single booster.

[CHRYNY]

Thanks. Those were the two options I was looking at. On this car it has auto - so probably the dual unit.