How special is it?

Are we talking about some badging or stickers or appearance package, maybe some wheels?

The Mustang Twister Special is not a run-of-the-mill regional special edition released by Ford in the late ‘60s/early ‘70s. It’s a lot closer to the highly collectible California Special of 1968.
The Twister had some serious performance upgrades that make it stand head & shoulders above the largely cosmetic additions offered on contemporary one-offs such as the Blazer Edition and High Country Mustang.
They were a huge hit in 1970 and to this day, Twister Specials continue to fetch high prices at auction

A PERFORMANCE MUSTANG FROM KANSAS

There were only 96 Mustang Twister Specials made & sold in Kansas-area dealerships for the 1970 model year.
Based on the already powerful Mach 1, the Twister Special added the drag pack suspension.
Originally all Twister Special Mustangs were to feature 428 Super Cobra Jet engines beneath their hoods.
Unfortunately, a shortage of these engines resulted in half of the cars receiving 351 Clevelands.
The R-code 428 Super Cobra Jet big block (335 hp and 440 lb-ft of twist) features the Drag Pack with the external oil cooler, while that manual comes with a Hurst T-handle shifter.
Buyers had the option of selecting from either a manual or automatic transmission

The 1970 Twister Special Mustangwere available only in Grabber Orange exterior paint and featured a black hood stripe along with custom “Twister Special” graphics
(installed at Ford’s assembly plant in Kansas City), with a black interior, a Shaker hood scoop (functional), Traction-Lok 3.91 gears, power front brakes, and power steering.
52 Twisters are believed to still survive today, of which only 18 feature the 351 engine.