Gasher

the pirate asked. “Do yer ken whatcher old friend Gasher just happens to have laid his hands on? It’s a grenado, something pretty the Old Folks left behind, and I’ve already tipped its cap—for to wear one’s cap before the introductin’ is complete would be wery bad manners, so it would!”

Man threatening the travelers with a grenade.

… Gasher. On the front of his cocked-back hardhat, the words LAMERK FOUNDRY stood out in black. Above them, a single staring eye had been painted. Gasher lowered the ’dozer’s blade. It tore across the lot on a diagonal, smashing brick, pulverizing beer and soda bottles to glittering powder, striking sparks from the rocks. Directly in its path, the rose nodded its delicate head. “Let’s see you ask some …

Man appearing in the vision driving the bulldozer.

“ Tower won’t be able to,” Jake said, “but what if he can?” He pointed at his other self, the one who had yet to meet Gasher and Tick-Tock and the old people of River Crossing. The one who had yet to meet Blaine the Mono and Rhea of the Coos.

Lud captor recalled in Jake's thoughts.

Swept from the stage, both of them. Into the clearing at the end of the path along with Gasher and Hoots, Benny Slightman, Susan Delgado (Calla, Callahan, Susan, Susannah) and the Tick-Tock Man, even Blaine and Patricia. Roland and his ka-tet would also pass into that clearing, be it early or late.

Dead adversary recalled in Roland's actual journey, not merely an unrelated fictional allusion.

He should have recognized the bridge, for they’d almost died on it in another world. Jake had been kidnapped off it by Gasher, and taken to the Tick-Tock Man. This was the City of Lud as it must have been in its prime. “Do you call it New York?”

Jake's kidnapper from the earlier Lud encounter, explicitly recalled at the bridge.