My 56 Dodge pickup came with no keys, ignotion or door locls. So what does a key blank look like for a vintage 50's era Dodge?

Andy, you may be able to buy matching door locks and keys from www.vintagepowerwagons.com or at least you could a few years back. The vintage Power Wagons used the 39-47 cab, but the more modern key & locks were an upgrade they offered, at least for a while.
Outside driver door locks were not even available on trucks until the 52 (or 53) model year and were an option for several years after that.

I bought and installed a remote power door lock kit on my 49. Haven't used it a lot yet, but that will change this coming summer.

When I got my 1 Plymouth I had three keys given to me, one of which actually fit something on the car. I took the door locks, trunk lock and glove box lock out and down to my local locksmith. He had what I needed to key new keys made. Now if you are looking for original Mopar keys, can't help there. I had a spare set made as well, $65.

This

https://www.ebay.com/itm/175569231184?

https://www.ebay.com/itm/275580276885?

those are pretty neat !

I don't know, I had a key one time for a 50s Dodge truck (the ignition switch it fit was self-destructing) that key was pretty small, looked more like the size of a lock box key but was thicker like more modern car keys. Old car company issued keys were not big, nor were they very fancy (at least the ones I've seen).

I used to have a couple zip lock bags of old car keys here, I found one bag, but it was mostly 70s keys. I haven't located the other bag, I know its here someplace, maybe it still has an older key in it, if I can find the bag....

48 Dodge key blank and key ring on ebay. Item number 394414395769
Only list fitting a 48 Dodge truck, but I suspect it covers more then that.

$27 + 4.99 shipping. Hopefully you can find it, I'm not so good with this stuff.

You did fine. https://www.ebay.com/itm/394414395769. At the top of the page just copy the http. addy and paste it in your post.