Apparently there were mods that could boost it to 340KT - however, that's still a long, long way short of 10MT.AFAIK they don't. 10Mt would probably involve a weapon delivered by B-52. Tactical weapons like those delivered by Pershing are in the kiloton range.
A 10Mt warhead would be a strategic system.
Tracked down the original reference in P&S. It talks of the weapon being a B.61 Mod 10 set for a yield of 10Mt. However that has to be a typo/mistake. The maximum yield of that weapon was 170 Kt.