I have two handsets for sale. They are in VGC and have the U-229A/U plug fitted. This is identical looking to the U-229/U plug that suits the 77 set but does not lock down.
They are the flat type handset (not a telephone receiver type), approx' 6" long with a hook athe top to hang them up.
Not sure what they're worth but will trust in the good members here to make an honest offer if interested
Cheers, Daryl