Adding a marque isn't the issue. Kaiser owned Willys-Jeep. Kaiser moved his car making branch to South America. He kept Willys-Jeep until the early 60's.
When you wrote about Kaiser leaving US auto production in 1955 and offering to fold the division into AMC I read that to mean the car operations that they exported as Industrias Kaiser Argentina rather than the distinct Willys Motors since they carried that on until selling it to AMC in 1970.
Packard divested its military related firms in the 50's. If the new AMC acquires and keeps these divisions during the 50's, it has a better base for defense contracts through the 60's.
Oho? I don't have much in the way of knowledge of Packard's military related firms, I was mostly thinking of vehicles thanks to having looked at AMC for a Chicago based automotive company timeline I was considering some time back. This is going from rusty memory and a couple of quick searches to refresh it so apologies for any errors.
In the ¼-ton light truck class Willys-Overland designed and produced the iconic Jeep during WWII sharing production with Ford, before going on to design its post-war replacements the M38 and M38A1 - the latter just before being taken over by Kaiser. Ford snaked the follow-on M151 but shared production with Kaiser and later the AM General division of AMC after the takeover. AMC also produced the M422 for a few years. When AMC was bought by Renault foreign government ownership laws forced them to sell AM General to LTV but the design and prototype contracts plus initial production order were made before the sale so I count it as an AMC vehicle. At around 280,000 Humvees produced that's money that could have helped fund other projects.
For 2½-ton trucks Studebaker made the US6 during WWII which was mostly exported via Lend Lease. REO getting the contract for the replacement M35 - although sharing production with Kaiser, later AM General - with production starting in 1950 which is before the formation of AMC. In the 5-ton class International Harvester designed and built the M54 along with Diamond T, Kaiser, and Mack. The replacement M809 was an AM General vehicle, as was the M939 which in turn followed it.
Altogether not a bad run. However, concerning the ¼-ton M151 if AMC have bought Willys from Kaiser might being part of a larger company with more 'heft' as it were and sites across a greater number of districts and states give them more lobbying/political influence? Fords not exactly a small company themselves but it could make things more competitive. For 2½-ton trucks whilst its ahead of AMCs formation if you go with the idea of Packard buying Studebaker during its brief insolvency and running it more professionally they might be in a better position to win. AM General already looks to have dominated the 5-ton truck field. It's completely up to the author.
If you want to get
really heavy-metal then there's always armoured personnel carriers specifically the M113. After WWII the US Army decided that APCs seemed like a good idea so twenty experimental M44s were built by Cadillac, the design however was
completely insane in that it was large enough to carry 24 soldiers. The follow-on M75 from International Harvester was moderately successful with around 1,700 being produced but was in turn replaced by the smaller and cheaper M59 from Food Machinery and Chemical only a couple of years later. Even after buying 6,300 the Army still weren't fully satisfied looking for something that combined the protection of the M75 with the size and weight of the M59 so issued a new specification. Kaiser Aluminum had been working on aluminium armour in the 1950s so FMC put in two proposals - the aluminium armoured T113 which had two variants, a thicker and a thinner armoured model, and the T117 with steel armour, with the thicker armoured T113 being chosen and after some more design changes becoming the M113.
If AMC bought Jeep from Kaiser in a friendly deal when they withdrew from car production, and provided that they didn't do anything subsequently to annoy him, might he decide to partner with them instead? With 80,000 variants being built and it still being in service that's a very decent revenue stream. You could even tie in International Harvester although that might be a little soon.
Edit: Apologies for the size of the post, only realised after it had gone through.