[Shop-talk] thunk going into reverse

[Tim]

I have a 92 ford tempo that both my daughters drove while in high 
school. It has now been mostly sitting for the past two years with some 
usage last summer and random weekends druing this time frame. It has 
less than 75,000 miles on it (original old lady car from GA when we got 
it six years ago with only 52K at that time. It had the original plug 
wires stamped with 1992 on them and probably the original coolant based 
on the chunky choclate milk consistancy.)

Anyway, I moved it yesterday and was reminded of the thunk I get after 
putting it in reverse (NOT during shift lever movement) and stepping on 
the gas. If my foot is left on the brake pedal, it does not thunk until 
after I remove my foot from the brake and press on the gas.

It does not seem to do this when shift into drive.

Is this CV axle or tranny?

Thanks
tim