GM automatic transmission names are encoded as such:
4 : Number of gears
T : orientation (L = longitudinal, T = transverse)
60 : series
E : only if transmission is electronically controlled
-HD: only if heavy duty diff is installed, and only on transverse layout as longitudinal layout has separate diff except for Corvette
Prior to the 4t60 the naming was not quite this standard. The 440t4 for example is the same as the 4t60, which are based on the TH125C case. Prior to this standardization, there were the TH125, 700R4, etc… names. Unless you're working on or restoring an older GM car or truck, you probably don't need to care about the older naming conventions (and probably will only need to care about the specific transmission in question for the build anyway).
The fact that it's an 88 GT doesn't make the install any more or less difficult. Swapping the 440t4/4t60 is the same level of difficulty regardless of what year/model Fiero you're doing the swap in (as long as it's being done on an automatic cradle). You are unlikely to find a brand new 440t4/4t60 trans anywhere, but you can probably get a rebuilt one (or just get a used one for cheap and rebuild it).
[This message has been edited by dobey (edited 09-20-2014).]
