 
It’s been a long time comming and they are Finally Here! The M226 (D44 Variant) Gears avilable for the rear of Nissan Titan Frontier and Xterra in both 4.10 and 4.56 ratios.
Superior – 4.10 M226 (D44 Variant) Rear Ring & Pinion Differential Gears – 2004 – 2007 Nissan Titan
M226 Ring and Pinion Set w/ 29-spline Pinion
Superior – 4.10 M226 (D44 Variant) Rear Ring & Pinion Differential Gears – 2005 – 2007 Nissan Xterra
M226 Ring and Pinion