Your outside compartment locks, assuming they haven't been changed by a previous owner, should all be the same 751.
Wrt the door latches, take out the four screws inside that hold it on, as well as the two on the side of the door. Pull it off and lube it. It doesn't matter what you use, but I'd recommend a spray lube like WD-40. It is best to lube after Step 4 when it's out of the door. It will penetrate the latch more this way. One of the first things I do to a new Sunny is take the door latches out to lube them, because I find the doors never slam shut if you push them when not lubed. They have to be shut by opening the latch. Otherwise, they'll bounce back and not move.
While you don't have to remove the compartment door latches, you will be surprised at how much easier they'll work if they get a few sprays too. You may also find the same key will work most, if not all locks. However, if you do upgrade locks, it is quite simple. One recommendation I have is if you do upgrade, upgrade to those special round key type locks. I hear these are a lot harder to pick / break into.
TO REMOVE A TRI-MARK RV DOOR LATCH:
Step 1: Remove 4 screws on inside of door:
Step 2: Slowly pull at the inside part of the latch to remove. Set on the side:
Step 3: Remove the 2 screws on the side of the door:
Step 4: Carefully pull out the latch assembly. It most likely will stick on the edge of the opening, so be careful not to crack the bubbled panel:
Here are some pics of what the latch looks like on the inside. It appears that the whole assembly is riveted together, so taking it apart wasn't an option for me:
Step 5: Reinstall the main part of the latch, from the outside:
Step 6: Reinstall the 2 screws on the side of the door. Make sure you take the shorter screws, not the longer ones:
Step 7: Reinstall the inside handle part of the latch. Make sure the flat spot on the red lock handle matches up with the flat spot on the lock post:
Step 8: Reinstall the 4 screws holding the inside part on:
Step 9: Check lock and latch mechanism to ensure proper performance:
Step 10: Check locksets with key to ensure key works well. If it doesn't, this is the time to refer back to step 1 and find out why it won't work:
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9473.8 (as of 6/18/21)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR