I disagree - I think the Heer would be better served by providing as many anti tank guns with a decent prime mover as possible across the entire army - thus giving a given infantry formation a better chance of defeating a Russian Armoured attack.
The problem with an SP AT gun is that the gun is lost if the vehicle is lost/breaks down.
So my opinion is spamming wheeled 75/48's anti tank guns across the German armed forces.
I think this was a better use of the gun and resources.
This my post from the Whale has Wings thread on US AT Guns
Original TOE for US infantry regiment was 18 guns, with Beeps or Jeeps as prime movers for 37mm in Africa, didn't work well, but AGF blamed crews for not using them properly, not that 37mm bounced off Mk IIIs, let alone Mk IV F panzers.
Finally, AGF agreed with critics in late May 1943 that half the guns should be 57mms, towed by 1.5 ton trucks, over Infantry Board objections that the 57mm was too heavy, but reason took hold, and 37mm were for Pacific deploying units only, and M3 Halftracks for prime movers.
During the Sicily landings, units were still transitioning to the 57mm, so some lucky US gunners got the experience of bouncing shot off of Hermann Goering div. Tigers. Some 5th Army units didn't have the 37mm replaced until late 1944.
Oh, and the US had a shortage of HE rounds for the 57mm, and had to use British stocks of HE ammo until after the Race across France was well underway, the Canister round so liked with the 37mm was not available till 1945
McNair was originally a Red Leg, so never got over his attraction to towed guns.
General Bruce(who wanted more M10 TDs) was overruled by McNair to deploy the 3" AT gun. It was the T9 tube from the AA gun from WWI, and was no lightweight. So the M5 3' gun came to be. It was over 200 pounds heavier than the towed 17 pounder, that itself was no lightweight. The PaK40 was 1500 pounds lighter.
General Devers while still at Armored Force, tried to get the 76mm T2 AT gun in its place, that had the same performance as the 3' gun, but over a thousand pounds lighter. One again, out maneuvered by McNair, the 76mm development was paused after he left AF.
Tank Destroyer Battalions would have a towed component, converting self-propelled units to towed, on March 31, 1943 using M3 halftrack as Prime Movers.
By time of D-Day there were 11 towed AT battalions and 19 self-propelled. The towed TD battalion was often permanently attached to an Infantry divisions on a one for one basis, SPs attached as an as needed basis.
before and during the breakout, the US AT guns were more often used in the direct fire infantry support role, remembering that the 57mm had limited HE supply
Major General Eddy, commander of VII Corps, called the 57mm guns 'virtually useless' a month after D-day.
And that was before Panthers were encountered in number. Along with HE rounds, US units began to draw the APDS from British stocks.
After Mid-July, AAA 90mm units were moved forward for AT use in First Army, attached to the TD Battalions HQ, and used mostly for direct fire infantry support and interdiction fire, being better at that job than the divisional 105mm howitzers.
In September 1944 General Bradley wanted only 12 towed AT Battalion in France, and then only if the would be converted to the new 90mm gun that was in development, the remaining 40 battalions to be self propelled.
Since the new towed 90mm AT was to be even a ton heavier than the 3" AT, nobody wanted it. They wanted M36s
during the Bulge, towed AT battalions had a 1:3 win loss ratio, unless the were integrated with an Infantry unit, where it improved to 1.3:1
First Army has 26% losses among the towed At units during the Bulge, vs 6-8% going across France
Of all TD losses 119, 86 of them were towed guns.
In February 1945 AGF decided that all regimental 57mm gun companies would be replaced with Pershing platoon, as available.