I've always thought Mr. Lindley's most used amp from that period was an gator-tolexed '50s Deluxe, both on stage and in the studio. Of course, when recording, he could have probably used whatever he had available, but I have some pics from the '75 and '76-77 tours and it appears to be that old Deluxe miked up in the backline. Almost all the classic "David" parts are his lap steel, but he did play Teles on stage, also. He's a tone-master in my book, and saw him solo 7 months ago, and to no surprise, he still has it, no matter what instrument he picks on- the talent and tone is in the head and the fingers!
BTW, Late For The Sky is my favorite JB recording, by far- thanks for mentioning it, as it seems like not many folks listen to it anymore?
I believe he has sold his Dumbles.