When Tom is kidnapped by Sollozzo he is carrying a sled and two large packages probably for his kids as a christmas present. When he leaves Sollozzo's den, they are gone.
Did Sollozzo keep the sled for himself?
To steal from Tom's kids! That's so cheap!

In a deleted scene, at the restaurant, Michael asks for the return of the sled.

In an old draft of the screenplay the following dialogue (omitted form the film took place):

In one scene:

Sonny - So did Michael make it to Sicily?
Tom - He's on the way now.
Sonny - Did Solozzo do anything else to you when you met?
Tom - He stole a sled I had bough for my kids.
Sonny - That Goddamned Tattaglia. I bet Phillip Tattaglia has it. I'm gonna whack that bastard.
Tom - Sonny, its just a sled. You can't go to war over a sled.
Sonny - Quit trying to gloss things over. I sure as hell wish I had a real consigliere like Genco.

Another Scene:
Vito - Tattaglia's a pimp. He never could have outfought Santino anymore than he could have taken that sled from Solozzo. Until this day I didn't know it was Barzini all along.

Tom - So what happened to the sled?

Vito - Solozzo gave it to Barzini's children for Christmas.

Tom - Should I negotiate with the Barzini people about getting it back?

TATTAGLIA: Yes, Don Barzini -- he's too modest. He had all the sleds. He refused to share them...

VITO CORLEONE: When -- when did I ever refuse to share? All of you know me here -- when did I ever refuse? -- except one time. And why? Because -- I believe this sled business -- is gonna destroy us in the years to come. I mean, it's not like skates or baseballs -- even parcheesi -- but sleds are dangerous, especially the red ones.

Don Detroit - I too tried to keep sleds out of my territory, but when there is white powdered snow, my men can't resist. I want sleds controlled. I don't want them near kids. I don't want them in schools. In my city we sell them in the dark areas. They're animals anyway, let them lose their sleds.

Don Corleone - As a reasonable man, I have come here to reason together.

Don Barzini - Then we are agreed. Sleds will be permitted but controlled. Don Corleone will give us protection in the East and there's the peace.

Manolo - ROSEBUD.

TOM- Should I insist all his men wear safety helmets when sledding?

Vito- Mention it. Don't insist...