My John Deere D105's plastic transaxle was starting to bog down going up hills so after investigating different options I settled on purchasing a Tuff Torq K66 transaxle and kit from RJR Tractor.
www.rjrtractor.com/
I also took this opportunity to add spindle bearings to my front steering as seen on Steve Stoltz video here:
ruclips.net/video/F-Alj_xvjJY/видео.html
Rear tires - simpletire.com/deestone-23-10.50-12-ds5246-tires
Lawnmower Towing Hitch
www.amazon.com/dp/B003D7MPWS/ref=cm_sw_r_cp_tai_8susBbXCZ9AAE
John Deere Cup Holder (and toolbox)
Part #: GX26165
John Deere Cover for toolbox
Part #: GX26166