[MBZ] some info please

[Landsart]

Thanks to all that replied a couple of weeks a go to my inquiry about a 240  
d , well in reading some more i believe i should settle on a 300 d , still i  
would like the 123 chassis , but should i be looking for one that has the cast 
 iron head or the one with the alloy one , i guess the change was made in 
1983 ?  is this an issue of concern ? Thanx for your reply .. Joe