Since you need an answer quick, can I assume you've already searched the site extensively for your answer?
I definitely did, but my search was bringing up tons of worthless questions and answers. A buddy also did a search and he found the answer in a post by Marlin, which didn't come up in my searches. Not a newb to toyotas or searches, just the Marlin board, it may take me a bit to figure out everything on here.
I found that the throwout bearing used for an R151F is in fact also the one for an 88 up V-6 with the 150. My Marlin clutch which was ordered for a 151 came with a throwout for a stock 86 without the 151. Luckily I got bell housing, t-case, and all shifters. Just have to trim my auto shifter opening now.