Xmsn fluid change?? Help

I'm a bit confused on this whole "sealed" transmission deal on these tacos.. I drive a 96 taco and I took my truck In today and the shop told me They couldn't check my fluid as the system is sealed... Can somebody please help me better understand how a vehicle can run 19 years on the same Xmsn fluid with this sealed system.

 

I don't know about a '96, but my '02 has a regular drain and fill hole. I've seen cars like that though, however there is always some way to get more fluid in. probably drop the pan to drain, then fill from a side hole in the transmission case somewhere. I have to say that this is the first I have heard anyone mention this issue on the 1st gen forum. Have you verified with your owner's manual?