[78targa]

I don't have the part number for the relay readily available, but I can get it this weekend for you.
It should be located next to the Lambda unit under the passenger seat. It is the little black square box with a single mounting hole in it.

Yes, your car will not run properly without it.

Do a search on this board for "Lambda Frequency Valve." I did an engine swap from a 1980 to a 1978 (and vica versa) last month. I tried really hard to pry the Lambda portion from the engine, but in the end the most economical solution was to transfer it over. What a pain in the @#^%!@#^ .

John Walker was very patient in his explaination as to what mods I would need to perform in order to remove it. I think the post covered the options fairly well, in case you are interested.

If you have any questions involving the transfer, where the system hooks up, ask away as it is still fresh in my mind.