help needed to find correct g/box

Hi Guys
i have been looking for and trying to find a 5 speed gear box for my nissan k10 but the trouble is i may sound thick or something? as i have had one sold me which i was told it would fit and no way would it on arrival of said g/box it was completely different i sent it back to get a refund then i found one that i was told it where from a 82/91 k10 five speed great i was thinking gets the g/box and yes it was the right one as one would think i got this fitted only to find its guess what its a four speed with a label as a five speed ? so has any of you boys got a five speed gearbox that will fit my little nissan they want to sell and no silly prices please
thanks for listening angi