Camper Shell ?
 

Will a camper shell that fits an 84-85 toyota shortbed, fit my 94 short bed?

(Not really sure of this) It may not match up to the cab- I have a Tri-Glass that fits my '91, and it seems like when dad bought it, he tried one that was made for an older truck, and it wouldnt fit. I think the cab on 3rd gens. is at a bit more of a slant.

Yup, it will fit. Won't be pretty but it will cover the bed.

The beds measure the same size.
But if the canopy matches the shape of the rear of the cab (instead of just straight up) then note that there is a difference between a std cab and Xtra cab canopy.