where can i get b4.1 parts not b4

[jampat2004]

trying to get the proper spares for my b4.1,tried loads of different shops on the net but cant seem to find anywhere that sells the proper b4.1 parts.
most of the shops i speak to are just saying they are same as b4.....they are not just carry the same part numbers which is stupid.
i need rear shock tower that is different to b4 but carrys the same part number but the tower is modified for lipo batterys and has different shock postions.
need a pair of standard b4.1 castor blocks which have 3 holes opposed to the b4 2 holes,and a rear chassis t piece which again is a different moulding.
so can someone point me in the right direction to speak to a person that understands that the two cars are different and use different parts.
thanks