Location for a block heater.

[Alfmv75]

I am a new owner of a 1989 B II XLT 2.9L auotmatic. The former owner included two new block heaters (different sizes) and no instructions as to which plug to remove.
Can anyone help me out with the proper location or which plug to knock out?
One (It may be a TEMRO #17890) measures 1.4 inches and the other one (WITH a cord) measures 2.275 inches. (I suspect that the larger one is not for the 2.9L V6. It was in a box of parts that came with the truck.
Thanx from Atlantic Canada.
Robert the newbie.

[Nobody]

I don't know, but I'm not sure it would really make a difference. I think I'd probably go for the freeze plug that is most accessible.

So how cold is it?

[Alfmv75]

I had the misfortune of having a similar event in my life quite a few years ago... Okay. Perhaps a couple of decades ago. I assumed that I could knock out the nearest or easiest frost plug (Sorry. I don't remember the particular car) only to find out that the cylinder wall was too close the the particular frost plug that I removed. The heater would not physically fit into the hole. I had to replace that frost plug (What a pain-in-the-ass that was) and still locate the correct plug to remove.
Temps here aren't any worse than Bangor, ME. We're almost parallel. Our weather is usually only about one day behind them.
We have had a very warm January with recent temperatures up close to 50. Then again, today it was closer to 18-20.
I may try a local auto parts store and see if I can borrow an instruction booklet from a similar block heater with similar dimensions.
Rob.

[ranger5.0]

I would call the local dealer and find out where they would install them or where the factory would. Since it must be a common item to have in your area, I am sure thay would have this info.