[Norm Peterson]

There is no such thing as a universal thread for shifters and shift knobs. They're all over the map, in both metric and SAE, coarse and fine threads. That your shift lever thread is "set in stone" means you'd need your adapter to somehow mate pieces of various male threads for the various shift knobs to the piece that threads onto the lever itself.

Performance Aftermarket Shifters
B&M™ (All models except Quick Click™): 1/2 - 20
B&M Quick Click™: 1/2 - 13
Barton - Camaro Shifter™ before 2013: 3/8 - 16
Barton - Camaro Shifter™ Flat Stick 2013 and newer: 12mm x 1.25
Barton - Camaro Factory Adapter™ 2013 and newer: 3/4 - 16
Barton - Challenger Shifter™: 12mm x 1.25
Barton - GT500 Shifter™: 10mm x 1.25
Barton - Mustang Shifter 2011BM-1™: 12mm x 1.25
EMPI Trigger Shifter™: 3/8 - 24
Ford Racing Short Shifter™ for '05 to '09 GT: 3/8 - 16
Ford Racing Short Shifter™ for '07 to '09 GT500: 3/8 - 16
Gennie Shifter™: 5/16 - 18
Gennie Shifter™ Commander: 7/16 - 20
Gennie Shifter™ Lo-Dapt™: 3/8 - 16
Hurst™ - 2016-17 Camaro Gen 6 Billet/Plus P/N:3916031: 9/16-18
Hurst™ - Auto/Stick1, Auto/Stick3, Billet/Plus, Competition Plus(newer): 3/8 - 16
Hurst™ - Pro-Matic, V-Matic, Vertical Gate (1987 and later): 3/8 - 16
Hurst™ - Competition/Plus (older), Indy Matic I, Indy 3 Speed, Indy SSA, Saf-T-Trigger: 3/8 - 24
Hurst™ - Quarter Stick, Quarter Stick II: 7/16 - 20
Hurst™ - Pro-Matic, V-Matic, Vertical Gate (all prior to 1987): 1/2 - 13
Lenco™: 5/16 - 18
Lokar™: 3/8 - 16, 3/8 - 24
Long™: 7/16 - 20
Lou's Short Stick™ - Camaro / Firebird™ 1993-2002: 16mm x 1.50
Lou's Short Stick™ - Dodge Challenger™ 2015 and newer: 16mm x 1.50
Lou's Short Stick™ - Pontiac GTO™ 2004-06: 16mm x 1.50
LSR Performance™ - Tri-Ax Short Throw: 12mm x 1.75
McLeod™: 3/8 - 24
MGW Camaro Short Throw Shifter™: 12mm x 1.75, 16mm x 1.50
MGW Camaro Generation 5 Short Throw Shifter™: Non-Threaded
MGW Camaro Retro Shaft Handle™: 12mm x 1.75
MGW Corvette Generation 5™: 9/16 - 18
MGW Corvette Generation 6™: Non-Threaded
MGW Flat Stick™: 3/8 - 16
MGW Mustang Short Throw Shifter™: 12mm x 1.25, 12mm x 1.75
MGW Mustang GT500 Shifter™: 12mm x 1.25, 12mm x 1.75, 10mm x 1.25
Modern Performance Dodge Dart Short Throw Shifter™: Requires our Dodge Dart Shift Knob Adapter
Mopar Short Throw Stick for '09-'11 Dodge Challenger™: 3/8 - 16
Mr. Norms Garage - Dodge Challenger Shifter Stick™: 7/16 - 20
MTI Racing Six Shooter™: 9/16-18
Pro 5.0™: 12mm x 1.75
Roush Mustang Short Throw™: 12mm x 1.25
Scat™- Drag Fast: 3/8 - 16
Serco™: 1/2 - 13
Shelby American™ - Generation 1 (up to 2011): 12mm x 1.75
Shelby American™ - Generation 2 (introduced in 2011): 12mm x 1.25
Steeda™ Tri-Ax '01 to '04: 12mm x 1.75
Steeda™ '05 to '10: 12mm x 1.75
Steeda™ '11 to '14: 12mm x 1.25
TCI Fast-Gate™: 7/16 - 20
TCI Street Fighter™: 7/16 - 20
TCI Street Fighter for '05-'08 Mustang™: 3/8 - 16
Winters™ - Sidewinder (Standard): 1/2 - 13

Norm