1955, not 1965
Assault rifles? Not yet. The AK is not in general use.The early models has serious issues with the receiver (among other things). They didn't start to reach the field in any number until '56/'57 onwards. The Eastern block is still using the SKS and Bolt actions (along with the PPsh-41 SMG). U.S. is still using the M-1 (M-14 didn't enter service until 1957). The FN-FAL is entering service, but there are still LOTS of bolt action rifles on the continent
1955: The AK-47 is being distributed to USSR troops en masse as the design is being refined, and as this is peace time in OTL there is no incentive to get the weaponry into the field as quickly as might be done in wartime
APC? Sort of. The BMP 50 is replacing the BMP 40 halftrack, but it is till open topped and the armor is more than suspect. The U.S. is beginning to deploy the M-59, but it is not in full use, most troops are still in 6x6s or on foot.
They are still more mobile than the animal-drawn transportation used by many countries in WWII, never mind that as the war progresses APCs are likely to get deployed in greater numbers.
Improved Spy planes? Compared to WW II, a bit, but not very far. The Mosquito was just as capable as a RF-94 & the wooden plane had longer range. The pictures are better, but the tech to use them is barely advanced from VJ Day.
The U-2 is flying by the end of 1955, the Canberra is up and running, and several other improved spy planes are in the air. Even the planes in 1945 are better than those in 1939, but by 1955 the designs are improved and another generation of telecom technology would refine the equipment inside them as well.
Aircraft? I would rather be in a F-86 than a Bf-109 as well. Problem is that BOTH sides are equipped with 1955 gear, so the other side has Mig -15 & -17, with the American Century series just starting to come on-line with the F-100 SuperSaber. With the early jets you didn't have the range of the Mustang and air-to-air is still a gunfight. Jets (well,second generation jets) can carry a heavier load, but they also take longer to build & there aren't as many jets around, the lethality jump just isn't there, not compared to the damage that could be wrought by the swarms of JagerBomber or Il-2s of the war years. The great changes will come later, with guided weapons and sub-munitions.
The AIM-4 will be operation in the US in less than a year, the USSR might be on its way with its own counterpart. The air war gets really interesting for a while...
Night vision? Not yet. The first practical starscopes made there combat appearance in Viet Nam. The IR of the era was crude, unrealiable and thin on the ground.
The US was using IR before the end of WWII and Germany was working on (deploying?) a man-portable system called "Vampir".
Transistors had barely begun to enter the battlefield in 1955. Virtually all radios and radar scopes still used tubes (hell, the Mig-25 IIRC had some tubes in the electronic suite up to the '70's). The miracle of modern tech, the guided weapon, has just begun to take it's first baby steps.
I was thinking more for radios, computers, and other telecom tech. That 40lb radio might now weigh 20. Guided weaponry is still a while away, though, you are right.
The biggest thing that hasn't changed in any significant way is the true killer of the battlefield; artillery. The majority of tubes are still towed, the supply train is still weak (even most of the weapons are WW II holdovers) There are still lots of 75mm in the park, with the 152mm & 155mm still semi-rare. The MLRS system is decades away, even the sub-munition won't be introduced until the late 60's (well the M-444 did come into use around 1962, but it wasn't really a DPICM).
No argument there. I wonder if a Skysweeper could be used as a nasty arty combo against large tank formations?
It was only in the late '60's and later, generally much later, that the modern, almost impossibly lethal, battlefield developed. A non-nuclear war in 1955 would have been bloodier than the 1942 version, since tactics had evolved, but it would, as the original question asked, be just as sustainable in terms of ground and air combat and the ability to resupply.
I think it would depend on the battlefield, especially as submarine technology would make the Atlantic a much more dangerous place in 1955 than 1940. Heck, Type XXIs would have made the Atlantic much more dangerous, never mind the Romeo, Whiskey, and Zulu-class subs the USSR would be running at the time.
This is the difference from today, where a major ground war between the major powers would be over in weeks, possibly two months at the outside. After that, the modern battlefield would be swept clean of the living and there would be no way to get new troops trainedand equipment built fast enough to make good losses.
Oh I think it would be bloody under this scenario, don't get me wrong, but the 1955-tech scenario (which, without WWII, is more like a 1970 scenario because of the tech leaps made during that time) would prove devastating. Also, if the tech differences like that of WWII are in place, and the US is 1955, where is everyone else?
The naval part of the battlefield was intentionally omitted by the original poster. This is, to a degree, regrettable, since it is in the naval arena that warfare actually evolved the most in the post WW II decade (and with the introduction of the SSN in 1954-58, was revolutionized).
Agreed, and I think that this could also make a major difference but we will leave it alone for now.