I have a 78 280z that has a 3 speed automatic, It shifts fine but after I get to about 50 mph it winds out and sound like its going to blow up, is it the differential or the transmission. Could someone please tell me. P.s. it has an r180 diff.

It's likely that the bands in your auto trans are slipping. Have you checked the fluid level and or changed the fluid?

Yes I have changed and checked the fluid, I took it to a transmission shop and he told me I would have to get my differential gears changed or get one from pick and pull. It shifts fine I dont think its the tranny. I also changed the filter in the tranny and put a new modulator valve on it.

Quite often when the pinion bearing in the diff goes the noise from this is transmitted thru the driveshaft and you swear the trans has blown up. Drain the oil out of the diff and check for metalic residue.

If the bands in the trans are that bad that they sqeal at 50 it would not change properly thru any of the gears.

Alan.

I already changed the fluid in the differential, it did have some deposits in the oil, I think that I do need to change my differential:cry: