Perhaps some pictures are in order. A maple interior ply would be expected for all 70’s Slingerland kit drums.

Here are some pics.

Follow/ click here Article III for shells

https://www.vintagedrumguide.com/drcjw/articles.html

Mahogany interiors on kit drums after 1964 are 'an exception to the rule'. They do show up on occasion, mostly on the larger 18" and 20" floor toms. Could you provide a picture of the 18" badge and serial numbers for all the drums?

This was back in the days before "just in time" and "lean manufacturing" so companies kept inventory for years if not decades so those were probably leftover shells from the 60s. Given slingerfan's observations on 18" and 20" floor toms, they might have had a surplus of shells in those sizes so they kept them for use in these two less common floor tom sizes.

Here are the serial numbers

Black/silver badge with serials in 130xxx's would be expected for ~'74. Do all those grommets appear undisturbed? Where is the bass drum?

The grommets and badges on the toms look undisturbed, and I took the lugs off of the kick, and there has been some yellowing/aging of the wrap, so I’m assuming that’s all original. I’m also assuming that when the second tom holder was added that the badge was removed. You can see from the interior pic some extra holes in the shell that I covered with a carriage bolt and a wide washer. I looked under the tom bracket closest to the edge to see if the badge was under it, but it wasn’t.

This makes the most sense to me. The serial numbers are fairly close in number. I really don’t think that there are any orphans in this kit. The yellowing/aging on the kit is all the same. I pulled off the lugs on the kick to clean it, and there has been slight yellowing of the finish, and to find an orphan that matches this would be darn-near impossible.