Dear VaRelics;
I tend to agree 101% with the prior statement from AUDuke. I operate an SD2100 and it goes DEEP. Digging up a burro shoe at 28" depth is about the norm, especially when used with larger coils. The SD2100 gets excellent depth with coils up 24". In my humble opinion, any bigger than 24" and the SD2100 starts to obey the law of diminishing returns. My advice to you would be to get a great pair of headphones, a Pocket Rocket battery pack and a GOOD shovel, my friend. And a good pick too, if the ground is hard. Oh, and a couple of friends, preferrably ones with strong backs, as they could come in very handy.
Your friend;
LAMAR