<VV> replacing a three speed with a four speed

[CORVAIR412 at aol.com]

I have a 1961 Monza coupe with a three speed and would like to replace  the 
drive train with a 4 speed drive train. I have the cross member which is  
attached to the transmission case of the four speed.  Clark's helps say I  also 
need the large cross member.  Does that mean I  will have to  replace the whole 
rear cross member?  Point me to a resource or to any  manual which would have 
the information.  Thanks so much
 
 
                                                            Dick Tetzloff  
Northern Minnesota