I bought a set of 15" Anco wiper blade refills from Autozone a couple years back and was just getting around to installing them only to discover they don't fit in the wiper blade holders on my GTX. So I need to find a set that will and was wondering if someone can tell me where I can find the correct style that will fit. Suggestions?

I buy break to fit refills at Advance and use the original arms.

https://shop.advanceautoparts.com/p/tric...fill+cut+to+fit

You can buy the Trico style on eBay https://www.ebay.com/itm/Classic-Wiper-B...0/291117070533?

Another vote for the Trico Classic 15" blades. No excuse for for running some Dollar Store cheesy blades on a 60's-70's vintage car.

The correct Anco pushbutton refills are really hard to get.
- Buy old stock.
- Find out who makes them for Classic Industries
They sell the blades and refills in 16"
but only the blades in 15"

The salesman said he'd ask to bring in the refills for the 15" but I think he's no longer there because my e-mails now don't get replies.

My Challenger and '78 Ford PU take 15". LMC advertises the blades. That is where I will try next time I need some.

http://www.lmctruck.com/icatalog/fc/full.aspx?Page=151

Local NAPA sells these. https://www.napaonline.com/en/p/TRI601647

I bought these

I'm not looking to replace the arms/blades as I want to keep the originals. I just need the rubber refills but need the type that will fit my blades. The ones I bought are too narrow and won't stay in the blades. They also don't have the compressible metal tabs that lock them in.

Exactly.
None of those look like or fit the Anco push button type blades.
Freshest rubber and best fit will be from whomever makes the blades for Classic Industries. Give them a call or shoot them an e-mail. Tell 'em you refills for their 15" blades, just like they sell for the 16" blades.

Freshest rubber and so-so fit will universal refills with the spring clips on the end. I've used them for years. IIRC this is Trico's "43" series, p/n 43-150. I've had universals from Anco (Anderson Comp.) with the spring clip tips that also worked. Not sure of the part numbers as didn't think this would ever be needed so I didn't keep track...

Older rubber, correct fit, will be Trico LP (latch pin) refills, or Anco PB (push button) refills. So interchange is
Trico LP-15
Anco 680
ANCO 12-15
NAPA 16-1512 (not verified with an actual example)