Chi-Ren Chen's Intrude2 puzzle

A difficult 6 x 6 x 3 puzzle consisting of a ring and four identical blocks. Fit the blocks into the ring and slide them around to make the final shape. No rotations required. Original design at http://puzzlewillbeplayed.com/663Ring/Intrude2/ I have included the .xmpuzzle file which can be loaded into Burr Tools if you need help with the solution.