prolly a known item by now but any1 scoopin up a 4.1 chassis off ebay to freshen up their b4 needs to know that the rear pivot block (losi verbage i know) is different and has different p# from old part. the chassis and thus the block have radius edges where as old b4 parts have square edges. old block will not work on new chassis, new block might work on old chassis, but best to buy old block for time being. just heads up.

R