Al - Try S & W Parts (a Forum Sponsor) because Bill Harrison has hundreds of Lionel parts and has been a Lionel Authorized Service Station for many years.  I believe the diaphragms you're looking for used to be product number #630-9124-047, but that part is apparently no longer available through Lionel.  Nonetheless if you contact Bill and just describe what you're looking for he'll tell you whether he's got it or not, and if he doesn't, he may know someone who does.  Bill's a great guy! 

Thanks!

@VegasTrains, did your search yield any success?

I used MTH diaphragms, attached using Walther's Goo.

@Mike Wyatt posted:

I used MTH diaphragms, attached using Walther's Goo.

Just looked on the MTH parts web site and they have a bunch. Do you remember which ones you bought.  I hate to ask for more work, but it would be great to see a picture of the finished product...

For those who find this thread, here is my finished product. I ended up getting the diaphragms from S&W and the number for me was 6109060010.  They worked great on my 6-39169 aluminum set. S&W is a pleasure to purchase from- fast shipping, nice folks, fair prices, no gouging on shipping.

This four- car set has a mix of end doors as the pictures show. For the deep openings, the diaphragms can be seated by simply pressing them in place.  For the other "short" door ends, minor clipping needs to take place.  One of the pictures shows the before and after.  I used goop to glue these short ones in place.  No interference on curves but I do not have 031 curves to run them through.  They were fine on 042. 

The diaphragms are a good match too with the MTH full vista dome that I added to this passenger set.

Here is a finished "short" door. the original view is a few pictures down.

Nice match between the deep door and the short door.

Good match with the MTH full vista dome. In operation, you can't tell the difference.

Here is what I cut off for the diaphragms on the short doors.

Original diaphragm you will receive from S&W.

Short door requiring the modified diaphragm. 

Original view of a "deep" door

Thanks for all your help!  I purchased a set of

610-9060-010

on the Bay... and they were a perfect fit.  I've now ordered a complete set fot the rest of the cars from Hennings.  They work great!

Jon