TH400 question

[76bonanza]

In an effort to find this whining sound in my truck I think it is the tranny. When it is cold outside I get this high pitch whine after I start it for a few seconds like 45 or so sometimes longer if it is real cold then it stops then when I put it in drive it does it again for a short time. Does not do it all when warm. Wondering does the th400 use gears instead of belts because that is kind of what it sounds like maybe untill the tranny fluid warms up? Any thoughts on this subject would be welcomed.

Thanks