Am I being taken for a ride?

[Southern Buckeye]

Greetings: bought a 69 shorty at the Mecum auction in Fla. in January. Has a 400 SB and a 400 thm tranny. It has a few problems that I asked a local shop to comb through to the tune of just of $1700. One of those probs was the rear pinion was leaking. They put a in a new seal and well, it was leaking when I got it home. It appeared like shaft had been cleaned off and area worked on. Now they're telling me that they have to open the tail housing and replace a bushing. Estimate is for another 1 to 1 1/2 hrs. of labor plus parts. Does this sound right? I am fair-minded but just don't want to be taken advantage of. I'm kind of handy mechanically, but my days climbing under a truck for hours at a time are long gone!! Thank-you in advance for your advice/opinions.