I hate paying 5+ bucks a can for any spray can cleaner ,you used to get carb or brake cleaner for 1.50 anywhere,now they bend you over for it..
I've found lemon juice works better than carb cleaner on really corroded lawnmower carbs,boil them in it for 15 minutes and they come out looking like brand new...
I used gasoline more than once to clean things like a diff,but outside and was very careful not to risk getting it ignited in any way--spraying gas or thinner is like a bomb waiting to go off under the right conditions..
And yes,laquer thinner is a ripoff now too,I remember selling it for 4 bucks a gallon back in the 80's..Mineral Spirits works ok,but is no cheaper than diesel fuel today...
I use a gasket and silicone RTV when I remove a diff cover,thats worked best for me...I've used just RTV a few times and it was OK for awhile,but it leaked at the bottom after awhile..that was back when "Ultra Blue" was supposedly Permatex's best stuff,I know they came out with at least half a dozen more colors and blends since,but I haven't used many of them,not having worked on much in recent years..The "right stuff" seems to get good reviews ..
I used Permatex #1 hardening gasket sealer once on a diff cover in a bind--next time it had to come off I had to litteraly chisel it off!..bent it before it came loose too!..stuff is like weld once it sets up..