Dipstick and vacuum modulator o-ring dimensions

[ChevDog1]

Looking for a bit of backup info before I head to the parts store today. I have a small transmission leak that is either the dipstick oring, or the oring on the vacuum modulator. The trans is a TH400. Does anyone know the correct sizes for these orings? My faith in auto parts stores is not what it once was. I used to have a parts guy at the local NAPA that could do this stuff from memory. Now they just look it up in a computer, and if you have a swapped in trans like I do, they can't help. Took me 20 minutes at the counter at AutoZone yesterday to get an ouotput shaft seal - I had to tell the kid that my truck was a 1978 C20 for him to find the correct part. Thanks!