1. include/blocks.inc.php has the switch on all the block creations.

line 52: comment out this stanza:
if ($CONF["Older"]>0 && $aln==$align) {
line 60: to here:
}

line 234: modify this stanza to your liking:
if ($CONF["Older"]>0 && $older_nrows>0) {
line 247: to here:
}

2: line 244: replace:
. stripslashes($A["Heading"]) .
with:
. substr(stripslashes($A["Heading"]),0,35) .

35 being the number of chars to limit by.

This is untested and thunk up while tipsy, so make a backup first.