Honestly...I really like both logos.

I think the original, or SYKCO works well on the front.

On the back...I don't want it to say "JYD"...I would prefer it as "JUNK YARD DOG #121"

Also, a simple statement etched into the back could also be awesome...straight from the Scrapyard Mission Statement: “performance first”

JYD #121
The chief cause of unhappiness and failure is trading what you want most in life for what you want at the moment.