Didn’t consider the Assassins as I had never heard of them. Looks like they are a few bucks cheaper. I like the idea of the adjustability but I think that’s just me falling for their marketing. Why would you ever not want to attach the connecting rod at the lowest front hole? That gives you the longest theoretical instant center. That’s why you use this style of setup vs a old style (and much cheaper) slapper bar. Same on the back, attaching at the lowest point gives the lowest load on the connecting rod. If you don’t attach at the lowest holes you just have wasted metal sticking down. I like the Caltrac method of attachment at the front. It seems fundamentally more robust than the bolted on bracket but does require removal of the leaf springs which is a pain on these trucks. Because the Caltrac front bracket bears on top of the leaf spring it will actual deflect the spring and raise the rear end under load. Not sure if that is a big deal 60’ wise but it will help keep it level.
From just pictures and specs I like the Caltracs. Don’t know about the comparative workmanship but the physics is better and the Assassin adjustability looks like marketing hype. ‘Assassin’ is pretty cool. I’m gonna say I have ‘Asphalt Attackers’.

Looked at the Assassin bars again. They say the front adjustment affects how hard it hits. Just because I don’t understand why they’re saying that doesn’t mean it’s not true but what I’m after is axle location control. I need to look closer at my truck to see how they would implement attachment with no u-bolts. I had to get new bolts for mine as the stock ones were too short for the Caltracs. No biggie just money. Also, the radius on the Caltrac lower axle bracket did at match the axle and had to be ground. Again not that big of a deal just more money. I’m going to ask them if they’ll reimburse me that part of the installation cost.
I was just looking at the bars and I see they have 3 adjusting holes in the front. Duh. Mine are set on the bottom hole which seems best.
Do yours really attach with no u-bolt? How does that work?
Also see the ears are not 100% welded to the bottom bracket. I suppose it’s okay strength-wise but if you’re in there welding anyway how much more could it cost?

Of course, all this is just talk from my standpoint as I’m probably not going to buy different bars based on internet urban legend. That being said, I measured how far the front connecting bar attachment hangs below the leaf spring pivot. Looks like 5 5/8”. More importantly it’s about 1/2“ behind the pivot. Assassin advertises their attachment with Berlin eye springs is 5 1/2” down, about the same. But because of the method of attachment it looks like it’s 2-3 inches behind the leaf spring pivot. That’s a bad direction. Caltrac IC is farther forward. Regarding angle of the connecting bar, Assassin says to begin with the bar high in the back as that gives a softer hit. I think softer hit must mean more axle wrap is allowed. So the higher attachment point and resulting shorter moment arm makes sense in that light. Guess I’m stuck with minimum axle wrap as my rear is not adjustable. For my 575 rwhp, 4wd truck I’m not sure how much all of that matters. Still can’t find a picture of the Assassin rear bracket attachment and don’t understand the no u-bolt/extra bracket arrangement. I did have to buy new longer u-bolts, they’re good ones and I don’t have any concerns. Interestingly the Assassin website shows their bars installed on springs with metal front bushings. I’ve been running my Caltracs with no preload and don’t notice any difference in ride. My biggest concern is wear on the metal to metal front bushing arrangement. I wanted grease zeros installed but the outfit doing the installation didn’t want to do it. It was slathered up with nickel never seize, I’m going to go a couple thousand miles, inspect the front bushings and install zeros at that time.
I’m really looking forward to checking new 60’ time. I was consistent 1.99.

The only thing that affects IC ic the location of the contact patch and the location of the front connecting rod attachment. You can draw a picture from there. If adjusting the location of the connecting rod rear attachment does not affect the stiffness of the torsion bar torsional stiffness how does it affect the ‘hit’? The rear attachment point does not impact IC. As the rear attachment point moves towards the axle the force in the connecting bar increases. Do folks ever have problems with the bolted on front bracket slopping or shearing the locating pin? I agree the the length of the connecting bar doesn’t really matter only the distance from the axle to the IC.
still don’t understand the rear bracket attaching with no U-bolts.
How do you define ‘hit’?

What affects the location of the IC is the location of the attachment of the front of the connecting bar and the loacation of the contact patch. Where the rear of the connecting bar is has no impact. If you don’t the distance of the rear connecting bar attachment point to the axle affects the torsional stiffness of the system how do you think it affects ‘hit’? The force in the connecting bar increases as the attachment point moves closer to the axle, as torque increases and as leaf spring stiffness decrease. Do folks ever have problems with the bolted on front bracket moving or shearing the locating pin? That would be a drag. Still cant picture how the no u-bolt rear bracket thing works.