i have a 91 civic dx hatch...it had a 91 dx tranny but it broke on me and i bought me a si one and it fitted with no problem...i just bought a zc recently and i used the same si tranny for the zc and the tranny is now making alot of annoying noises. i was about to buy another tranny but the person that im buying it from said do i want a 20 spline si tranny or a 21 spline si tranny? wats the difference and which is better? wat should i use?

 

i think the 21 spline is the 88 si trannys that has a smaller clutch disc and i think the 20 splines is for 89-91 si trannys.

 

hmm that sounds right...does anyone know for sure

 

im sure this is right infromation on what i said. i looked it up. i suggest you use the 20 spline, because you got a 91 hatch.

 

I can verify that 88s have 21 spline