I have a D16Z6 in a 88 lx. I did not do the swap. Im not sure if the person who did the swap used the stock tranny or if they used a si tranny. So my question is how would I be able to tell if it is the Lx tranny or a Si tranny?

I'd get under the tranny and look for some number on it then research the number u find....prolly ur best bet!

probably. but im sure somebody around here knows exactly what number to look for and where and what the number means.

you should be able to tell by the feel of the tranny. there is a large drop in rpm between 1st nad 2nd if you have the lx trans. i found that reikoshea has a sticky on this. you should go check that out when you find the numbers on your trans. it tells you the gear ratios of the trannies and what models they come in. i'll try to pull up the link. http://hondaswap.com/reference-materials/honda-transmission-specs-29132/ that should take you there.