Quote Originally Posted by Gambit View Post
Just a heads up that I also had to bore out the rear O2 sensor hole of my '88 4wd to allow the new sensor to fit (Denso #234-2062. ​Wasn't a huge deal, but it didn't plug right in.
For anybody else doing this, Toyota used 2 different rear sensors in 1988, but now both are obsolete and cross-over to a single part number (Toyota #89465-29336). That part number is supplied to Toyota by Denso (Denso #234-2062), so if you're after OE (in my opinion the best), and don't want to pay extra for the little red box that says "Toyota" on it, then this is the one you want. It is specifically for 88 - 89 vans and will work in the rear sensor location only. And yes, on some vans you will likely need to bore out the hole a bit (I know it's a PITA). It's possible some aftermarket sensors will fit without the mod, but I couldn't say which ones and/or the quality you could expect. Tim