Many shops have fluid exchange machines that will swap 100% of the fluid via the cooling lines. I had mine done at the local Valvoline Rapid Oil Change (I know Jiffy Lube does it too). And they had no problem checking the level, their book told them there was no dipstick and directed them to send a guy in the pit under the vehicle to check level at the fill port.

Steve Carlson - 95 Trooper LS expo rig
Serenity now!