All CRX transmissions will be labeled as being an L3 transmission. The number of rings (grooves) on the input shaft tell you which year that it is from. 0 rings = ’88, 1 ring = ’89, 2 rings = ’90-’91
To identify which type of gear set it has, you can use the stampings on the outside of tranny case, just above the fill hole. There is a round stamp with some numbers/letters. All these do is specify bearing sizes. The Si usually had larger bearings and this is reflected by a code of PL3/3000 and sometimes 9000. If it says PL3/A100, the tranny has smaller bearings and is probably a DX, or HF model. I say “usually” and “probably” because Honda did produce some small bearing Si transmissions. If the round stamp is blank, it’s an ’88 transmission and you cannot determine the gearset by this method.
DOHC ZC transmissions use a larger differential with thicker axles. You can identify them by the larger hole where the axles plug into the differential.
From a crxcommunity.com posting on L3 transmission identification:
Identifying a transmission by visual inspection
All CRX transmissions will be labeled as being an L3 transmission. The number of rings (grooves) on the input shaft tell you which year that it is from. 0 rings = ’88, 1 ring = ’89, 2 rings = ’90-’91
To identify which type of gear set it has, you can use the stampings on the outside of tranny case, just above the fill hole. There is a round stamp with some numbers/letters. All these do is specify bearing sizes. The Si usually had larger bearings and this is reflected by a code of PL3/3000 and sometimes 9000. If it says PL3/A100, the tranny has smaller bearings and is probably a DX, or HF model. I say “usually” and “probably” because Honda did produce some small bearing Si transmissions. If the round stamp is blank, it’s an ’88 transmission and you cannot determine the gearset by this method.
DOHC ZC transmissions use a larger differential with thicker axles. You can identify them by the larger hole where the axles plug into the differential.