Phil,
The rev. 10-1 69 GM 69 P&A (Parts Book) that I am using only shows one oil pan 3958657 (group # 1.426) for 65-69 Chevelle and Camaro. I was hoping that someone would have a 67-68 P&A that could verify these numbers.
I think the pans are the same because the sub frames (67,68,69 Camaro) are alike except for frame to engine mounts and some minor stampings ( front rad. support rails etc.).
The 67 dipstick and tube are at least 2" shorter than the 68,69. I think the reason for the redesign in 68.69 was the C60 AC option for BB's
Let me know if you find anything to the contrary.
Bob C