Inside The New ZF 8-Speed
Randy’s Transmissions breaks the seal on the new automatic behind the ’25 Cummins, Jelibuilt discovers the ultimate 600hp 7.3L recipe, and truck pulling commences across America.
Just how tough is the all-new, ZF 8-speed automatic found in ’25 Ram heavy duty trucks? In a recent teardown video, the folks at Randy’s Transmissions had nothing but good things to say. Triple-disc, steel converter, beefy clutches and thick steel drums employed to hold up to big torque, and anti-drag wave rings used to keep clutches from dragging after they’re released. Other than the ZF’s remote, chain-driven pump arrangement (which is unique to this segment), most of what Randy’s came across inside the case resembled the other ZF transmissions already on the market (computer and solenoids all integrated into the valvebody, same P1 and P2 planetaries, same input shaft, same plastic pan with integrated filter). Of course, there is always room for improvement—and Randy’s already has a few things in development for the Cummins-compatible ZF. Expect them to lead the way on this new transmission platform.
In The Dirt
Smalltown Sled Pull—Big Name Competition
It was a busy weekend both on the east coast and in the Midwest for truck and tractor pulling. Friday night, we found ourselves at the Lincoln County Fair in Troy, Missouri to take in some Hot Shot’s Secret Pro Pulling League action in the form of Super Stock Diesel Trucks. There, Missouri native Keith Witt earned the title of hometown hero after covering more than 359 feet behind the wheel of his Scheid-powered “American Pride” Ram. The Limited Pro Stock Trucks were on hand, too, with big names like Jason Wayman (“Megatron”), Skyler Leeper (Legal Limits), and even Austin White (trekking over from Kentucky) in the house with “Gambler.” However, when the dust settled in Limited Pro Stock, James Deverman’s “Chain Smoker” got the win.
Hassler Diesel’s New P-pumped 7.3L Super Stock Puller
It was the debut weekend for Tommy Hassler’s latest puller: a tube chassis Super Stock truck wearing a brand-new Super Duty wrapper and packing a P-pumped 7.3L Power Stroke. It’s a project many Hassler Diesel fans have been waiting for and the truck’s first test-hook did not disappoint, with the big single turbo’d V-8 turning more than 6,500 rpm. Addressing a small valvetrain issue after the pass, Tommy loaded up and traveled to Leesburg, Pennsylvania the following night to compete with the likes of Norman Newswanger (“Chapter 11”) and Carl Ankiewicz (“Livin’ On The Edge”). Thanks to the the truck’s 2025 King Ranch F-350 body, it’s been coined “Twisted Addiction, King Ranch Edition.”
A Unique Truck In A Unique Class
The first contest for the Illini State Pullers’ 6,500-pound Light Pro Stock truck class commenced over the weekend, and our friends at Wehrli Custom Fabrication made the most of it. Thursday evening, Jason Wehrli piloted “Legally Altered,” his Duramax-powered ’76 GMC to the front of the field with a 328.40-foot distance. 48 hours later, Jason and his 6.6L-powered square body turned in a repeat performance, winning with a 324.21-foot effort. The ISP 6,500-pound Light Pro Stock class itself is interesting, with regular cab trucks getting the nod to make weight (no fiberglass is allowed), OEM frame rails being mandatory, and engines being limited to running a 3.0-inch smooth bore turbo.
Dirt And Drags: WP Developments’ Plans For Double-Duty
You won’t find a more motivated group of individuals than the people working at WP Developments. The transmission experts from Otterbein, Indiana have gone all-in in both drag racing and truck pulling recently, and they’ve got something unique up their sleeve for this year’s Scheid Diesel Extravaganza. Company VP, Ethan Patterson, not only plans to improve on his 68RFE record on the Wagler Motorsport’s Park drag strip (a 5.66-second eighth-mile at 125 mph set in Bowling Green last year), but he’ll also climb behind the wheel of O-Line over in the dirt, the Super Stock pulling truck he, his team, and Indianapolis Colts Offensive Guard, Dalton Tucker, have collaborated on. As for the latter truck, it’ll soon be breathing through the triple-turbo arrangement pictured above—and be fueled by a Fair Valley Performance Sigma pump…
On The Dyno
The Ultimate 600 HP OBS Ford Recipe
As if the looks of a standard cab, OBS Ford sitting on Super Swamper Boggers weren’t enough, Jelibuilt Performance’s shop truck is also belting out 614 hp and 1,312 lb-ft of torque. Still a 7.3L Power Stroke, still HEUI, still chugging along. To breach the 600hp mark, the F-350 was treated to 275cc Unlimited Diesel Performance injectors with 100-percent over nozzles, a CNC Fabrication Stage 2 high-pressure oil pump, an Irate Diesel Performance competition fuel system, and Jelibuilt’s own fine-tuning of the PCM using Power Hungry Performance Minotaur software and a Hydra Chip. Other key pieces include an Irate T4 turbo mount, an S467.7, ARP head studs, Comp Cams beehive valve springs, Manton pushrods, and a built E4OD from Twisted Diesel.
Written by Mike McGlothlin
