Here's an idea I came up with over the weekend. I have always used permanent marker to record information about oil changes, etc on some light colored accessible part of the underhood area, but it was always a nuisance, having to get alcohol to update the information.

So I decided what was needed was a place to leave real notes. I installed a clear plastic CD holder (jewel case) on the forward edge just above the battery. Used the holes for that data plate in fact. this lets me stick some white stickers in there and record all my vital data, and the nice plastic cover keeps it clean.

the data cover screws will work to hold it in place, but they won't quite allow the the cover to drop back down and seal 100%, so I used a pop rivet gun to hold'em down. I used one of the mini CD jewel case, as I figured smaller was better. Hopefully being on the forward edge, heat won't do too much damage to the clear plastic
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'88 740T 161K, '90 740T 231K, '95 940T, 71K plus a few Corvairs