im looking to swap out my auto for a manual and a locale auto wrecker has two different trans and i need to know witch i need. I have a 89 si and a doner car a 91 S(has an auto). The two trans he has are a d2a4 and a d2l5

Where are you located? In the US, the fuel injected 89 Prelude came with a D2J3 transmission and the 88 came with the D2J5. 90 and 91 came with the D2A4. You can use either the D2J3 or D2J5 with no issues. You can use a D2A4 as long as you use the flywheel and clutch kit for a 90/91 Prelude. You would also need to modify the VSS to work with that transmission. I've never heard of a D2I5.

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1991 Prelude Si ALB 4WS
2017 Ram Rebel

I thought the 90-91 had different spline wheel hubs? Hope the splines in the trans are the same? Can't remember.

You correct about the hubs being different. But the spline count on the transmission end is the same. On the 89 I used to own (now owned by mu son) I swapped the front hubs with a set from a 91 Si. I had to go with 90/91 axles but it still has the original d2j3 transmission. He doesn't have to change the axles.

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1991 Prelude Si ALB 4WS
2017 Ram Rebel

Good to know!