58- upper or lower trans crossmember mount holes?

[WSSmolick]

I'm installing a '66-'68 Saginaw 3 speed overdrive into my '58. For the transmission crossmember, which frame bracket holes do I mount it to; upper or lower? I can't find anywhere where this is mentioned. The shop manual has a pic of an original 3spd OD where the crossmember is mounted to the lower holes.

 

[gearhead409]

the only time the upper holes are used on the 58-64 chevys is with the three speed trans without overdrive.