Here's a review by Cookie Sewell of the Nashorn kit that mentions the #6004 Hummel:
http://www.kitreview.com/armourreviews/nashornreviewcs_1.htm
To quote: "When they released their Hummel kit (No. 6004) they corrected many of the hull problems with the Nashorn kit, but it was still considered to be a bear to assemble correctly and get all the parts to fit right."
M.