Subtract Last Three Characters!

Hello everyone. I have a query where I pull all item_codes that start with a 7. I need all the item_codes that start with 7, but I need to subtract the last 3 characters from only the item_codes that are not 71860kit or 71851nggun. How would I be able to accomplish this. What I have below subtracts the last 3 characters from all item_codes including 71860kit and 71851nggun. I want these two to stay in tact when I select them in the query.

This is the Query that I have now!

select datepart(year, date_cust_invoice)as INV_YEAR,
datepart(month, date_cust_invoice)as INV_MONTH,
item_code=left(item_code, len(item_code)-3)
, sum(QTY_SALES)as QTY_SALES_TOTALS, sum(SALES_VAL)as SALES_VAL_TOTALS
from opcsahf
where datepart(year, date_cust_invoice) >= '2003'
and substring(item_code, 1, 1) = '7'
group by datepart(year, date_cust_invoice), datepart(month, date_cust_invoice),
item_code
order by inv_year, inv_month, item_code



All help is appreciated!