Yeah, theres a drain and fill plug on the back side of the transfer case. The kind of fluid all depends on the type of transfer case you have. If you have Auto4wd or AWD (rare in a blazer), you'll need to use the GM Autotrak II fluid. If its just the regular push button 4wd, then regular ATF will do.
Hopefully you have a small hand pump to fill it. There really isn't room enough to get a bottle up in there... I used my air hose to pressurize the bottle with a hose up into the fill hole. I really wish I had some 1/4" hose to do it with... The 3/8" hose wouldn't fit and my only other option was 1/8" and that took FOREVER!!!
Thanks for the info man thats exactly what I was looking for. Also on the cooler I have my external coolers mounted on my Ls1 in front of the condensor. I bypassed my stock cooler on the LS1. I'm pretty sure the input/output lines to the trans are the same on the blazer right? Input bottom line and output top off the radiator?