stupid question.... answer needed

I tried a little while ago to get the plug out of the back of the rearend cover on a 7.25 rearend that is in the 69 Valiant and it wouldn't budge. I have to get it out this week somehow for sure but the question is : is that where you check the fluid level on this rearend. I don't have it in the garage right now and I really didn't look but it seems to me that the plug was awful high on the cover. is that where you check the level. remove the plug and stick you finger in one joint. I have only messed with an 8 3/4 so this is new to me. I didn't want to get too much fluid in there. I will probably have to remove the cover and heat the plug and replace the gasket.