I just did my 154 freeride to a 156 3", cost was around $1750 that includes a offset rear axle.
I recommend buying a t-3 drive shaft w. 7tooth drivers already on it for around $380 rather then avid 7 tooth with our current exchange.
Thanks for the info guys. My track has 1300 km's on it, none in the mountains, ridden by old guy back and forth to the fishing shack on the lake. Looking to get $1200 for the track and the drivers if anyone interested.