I'm not sure if I made you worry about the 5 speed transmission being "different" than the later sealed transmission but don't worry they are the same transmission the only real difference is the "sealed" part and Toyota changed the type of fluid to one that would last a "lifetime" which is a load of crap, there's no such thing as a lifetime transmission fluid or any other type of oil, any lubricate will lose some if not all of it's lubricating properties after a certain number of miles, also Toyota "may" have changed some other minor things since the WS fluid has a lower viscosity but the transmissions are basically the same with the exception of one having a dipstick and the other not, that being said the WS fluid was engineered to have a longer service life over older fluids but Toyota says can't be used in the non-sealed transmission because of the lower viscosity, that's why you need to use the T-IV fluid.

When you pull the dipstick and look at the trans fluid also smell it, even if it looks dark and not cherry red but smells more or less like new transmission fluid everything should be fine but it might be a good idea to do a fluid change, if it smells like it's been burnt the transmission might have over heated at some point but if it shifts fine when driving it there may not be any issues from it overheating but I would definitely change out the fluid in this case.