I would not hesitate to ask. You are about to plunk down a good sum of cash. If the owner is concerned about cross threading or some other damage, I agree that you can offer to have a professional mechanic do it.

It may not be the norm, but for any car that I have sold, I have been very forthright about any problems with the car, and have priced it accordingly. I expect the same from others and if they are embarrassed about something I have found that they knew about and were not telling, shame on them. My approach is to establish what the seller wants, and ask if there are any problems that I should know about. Then if I find problems during my inspection, my offer goes down accordingly.

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85 300D 75K Anthracite Grey 0-60 in 13 seconds **For Sale**
84 300D 333K Black (The Velveteen Rabbit) 0-60 in 14 seconds
00 Toyota Sienna 208K (Sold)
15 Subaru Outback 43K
11 Subaru Outback 67K
98 Ford Taurus 100K (Gertie - Was Grandma's - drove it to church and shopping - really) Daughter's car now.
30 Model A Ford 2 Door Sedan (Sold) 0-60 in . . . Never reached 60