How cold is too cold?

Temps for Saturday high of 32F.  Plan on sealing up the trans/diff for the
'87. I have an unheated barn where the trans and differential are now and
also an unheated garage.  The garage is attached to the house, so it is a
bit warmer.  I need to seal the transmission pan, differential and have all
other gaskets, filter and seals to apply.

If I ran a kerosene tube in the garage, could probably get it to 50.  I'm
sure these parts are sensitive to temps and don't want to have anything
leak.

Thanks for any info.

Pete
'79 Westy "Aardvark"
'87 Westy "JoesVan"
WWW.Busesbythebeach.com