classsic impreza rear diff question

a mate of mine has a classic impreza diff in his shed and hasnt a clue what the final drive ratio is or if its an sti diff or what
all he knows is that it takes the bigger female drive shafts (his words not mine)
is there anyway of knowing what type of diff it is just by looking at it or is there any markings or stamps on the diff to let you know what the ratio etc is
cheers lads

howdy all, got bored today so meself and my mate took the cover off this diff and found the numbers 40:9 stamped on the large part of the diff, the part with all the teeth on it (sorry about the discription )
so i done a googe search and all of the info ive found is that its a 4.444 diff....
so we know now that its a 4.444 rear diff which takes the bigger drive shafts so my next question is what classic impreza model is it off

AFAIK, the only classic Impreza with bigger half shafts is the type-R & RA

was just told that the diff looks like an r160 diff, is this the same as the diff in the type r or ra

r160 is a wrx diff r180 for type r most likely thats what it off with that ratio

Type R & RA have R180 rear diffs, same as newage Sti's. These take the bigger shafts whereas the R160 diffs are in all other classics and newage wrx's and take the smaller shafts

probably not a r160 diff so, this diff takes the bigger drive shafts.....