Advice on cleaning the inside of W56 tranny

[dreys77]

First off, to understand why I'm posting this is cause I'm super anal by nature, sometimes it sucks to be like that, sometimes it's a good thing. My question is...is there any way of cleaning the inside of my tranny without cracking it open? I have some time off and I'm TOTALLY going through my 88 4R. It has a W56 manual tranny with about 300k. I can tell that somebody has already gotten into it due to the orange RTV spooge around the mating points, probably a previous rebuild. Honestly, it works alright, but I'm going to mate it to a 5MGE and want to make sure that it's in optimal condition, without a rebuild. As far as I know (not to much about man trannys), it's basically gears and bearings. Here's my thought, and it might be crazy, especially after reading the "never change your tranny oil" post. Drain it and the t-case. Plug them up, remove the shifter plates and dump a gallon or so of some acetone (or someting with a high flash point) down there, shake the heck out of it, drain it, and flush with some more solevent, let it dry out and top it off with some good, new gear oil. Is this a hairbrained idea, or will it do some good? Can I screw anything up by doing this? Thanks....