TRD ke70

that's a Mazda gearbox out of RWD 323 fa4ts model using at uc or tc engine. NOT TOYOTA. hope that helps.

try putting a 7K out of a SBV toyota townace(1800cc)efi or carby, that'll scare the crap out of your auto.

the gearbox problem or nosie is caused by the lay shaft bearings,the reason it's quite in 4th only is that the lay shaft isn't used, it's a straight drive through when in 4th.the lay shaft is used in 5th as well. the only fix is to pull the box down and replace the bearings, but check the shaft for wear as well, up until a couple of years ago you could buy new shafts with bearings from toyota for about $90. not sure about now! if you don't know what the layshaft is, it's the first set of gears you see when you remove the pan off the gear box. hope that helps.