What was this hole in the floor and bolt in tranny for?

[oldcarnut]

I pulled the carpet out of my 70 SB Clone project yesterday to check the floor pan condition and saw this hole cut in the floor tunnel with a bolt going into the tranny.  None of my other trannies have it.  There were two other holes in the firewall like it used to have add-on AC so I wondered if the hole was for a drain line but I don't get the bolt in the tranny.  It's in the main body and not the bell housing.  Anybody seen this with add-on AC or have an explanation?  I didn't back the bolt out to see if it was a blind hole but it's 1/4 - 5/16 thread size.  The floor pans were in good shape and there was an outline of an "S+" under the paint.

[John_Kunkel]

It's possible that the A/C installer who drilled the hole in the floor for the drain didn't stop and went on into the trans bellhousing. The bolt might just be filling the hole. 

[lisiecki1]

with the small hole next to it it looks like it had a cover at one time also.....interesting.....

[covet66]

Aftermarket tach with a hole for wiring?

[TylerCharger69]

I dunno....that's anew one on me....no 727 TF I know of has that.....assuming it's an automatic....

[oldcarnut]

It's possible that the A/C installer who drilled the hole in the floor for the drain didn't stop and went on into the trans bellhousing. The bolt might just be filling the hole. 

I didn't think about that possibility  . I'll back it out later this week and see how far it goes in.  Thanks all for the input.