Shaft in a driving iron?

I have a ctaper lite in my tm 2 iron and love it. Couple lads at the club use tour ad graphite shafts in tmbs and get on great with them, not sure on the specs though. I tried one of them as the guy was my partner in a foursomes practice, it feel ok to me, just couldn't justify the cost to change when I dont feel the need.
Do u know anyone who has one you could try?