What types of things have you tried with him (other than halters and the like)?
I've noticed this is a trend with labbys.....and mine is a little over a year and still using a Halti, but it has gotten a LOT better! I'll let you know some of the things I've been doing, but since you've been training I don't want to tell you things you may have already tried! No point in being repetitive....
Chase (Friendly Resident Wigglebum) - Border Collie/Lab/Shepherd X
Kailey (Misunderstood Gentle Beauty) - GSD & foster failure #1
Rupert (Gold-Medal Winner of the 3 a.m. Kitty Destruction Olympics
Heidi - RIP my sweet baby girl