The CRB-27 Crab has been in the service to the DCMS in some numbers ever since the War of 3039. Sadly, while the design was adequate to face off against the best the Federated Commonwealth had to offer, the coming of the Clans proved it and many other DCMS designs incapable ot standing up to the Clan threat.
      
     What really vexed many a Combine Crab pilot was the inability to compete with the Ryoken. For a mech only 5 tons heavier, it packed a weapons fit that seemed to be 3 times that weight. Many a Combine warrior became desperate, and their after action reports reflected their frustrations, especially when they engaged the Clanners one on one (suicidal, but a favored Combine tradition nonethless)

   Obviously, something to deal with the problem was needed, and a minor designer at Luthien Armour Works hit upon a solution in early 3052. Why not simply upgrade the Crab? Design studies were undertaken, and it was found to be possible, if some tradeoffs were accepted. The Coordinator was shown the plans and both he and then Kanrei Theodore were pleased, and directed that production on the improved models begin as soon as possible.

   While there were some delays, and cost overruns, the design rolled off the Luthien line in early 3055, and was sent to the Ryuken for field testing, the results were impressive. It could, if used properly, have something resembling a chance against the Ryokens, and in it's first combat during a Ryuken-Go raid on Avon, it proved a rude shock to the Smoke Jaguars.

     The largest change in the new model Crab is the increase in speed, While the XL engine makes the mech more vulnerable, it is a tradeoff that many Combine warriors accept with gusto.
    
     Another selling point of the newer Crab is the fact that many of the older components have been switched out for locally produced ones, and that more firepower has been added in the form of 2 Lord's Light 2 ER PPCs, which give the Crab the punch some say it lacked.

     In 3058, a variant was designed in cooperation with the CMRF, it dropped 3 Double Heat Sinks and added Triple Strength Mynomer and Jump Jets to give the mech even more mobility, and an unparalleled close range punch.

       The mech has been deployed to many units in the DCMS, but is most common in those closest to Luthien, or those with a higher amount of Star League 'Mechs. The mech is especially common among the Ryuken and for some odd reason, the Benjiamin Regulars.