It's doubtful that just replacing synchro's will help with a tranny that's jumping out of gear. It's more likely caused by worn clutch dogs on the gears (the parts that actually engage), or possibly badly worn bearings. When the gears can move relative to each other, that motion makes the dogs walk out of engagement.

The clutch I bought (although a 9") for my 51 216 was a Luk brand, which should be a good choice.

I thought Canadian Tire was the Harbor Freight equivalent in Canada. I bought a pair of jack stands at Williams Lake on a trip down to the lower 48 when I needed to do some work on my truck in a motel parking lot.

Kevin
1951 Chevy 3100 work truck
Follow this saga in Project Journal
Photos
1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.