Your probably can't go wrong with either one. The Marlin Crawler product is a new design and the Longfield appears to be OEM speces other than the materials. I'd call Marlin Crawler and discuss it with them, you may be able to purchase the Longfield from them if that's your choice. I'd think that the Longfield would be more than adequate for the majority of people and suspect that the Marlin product is stronger due to the 30 spline design and it's also chromoly (it doesn't specify if it's the same 4330 that the Longfield is). The price difference accounts for the additional parts that are required for the Marlin unit.